Publicly accessible
URL: http://nzetc.victoria.ac.nz/collections.html
copyright 2006, by Victoria University of Wellington
All unambiguous end-of-line hyphens have been removed and the trailing part of a word has been joined to the preceding line, except in the case of those words that break over a page. Every effort has been made to preserve the Māori macron using unicode.
Some keywords in the header are a local Electronic Text Center scheme to aid in establishing analytical groupings.
Tuatara aims to stimulate and widen interest in the natural sciences in New Zealand, by publishing articles which (a), review recent advances of broad interest; or (b), give clear, illustrated, and readily understood keys to the identification of New Zealand plants and animals; or (c), relate New Zealand biological problems to a broader Pacific or Southern Hemisphere context. Authors are asked to explain any special terminology required by their topic. Address for contributions: Editor of Tuatara, c/o. Victoria University of Wellington, Box 196, Wellington, New Zealand. Enquiries about subscriptions or advertising should be sent to: Business Manager of Tuatara, c/o. Victoria University of Wellington, Box 196, Wellington, New Zealand.
(This issue edited by
is the journal of the Biological Society, Victoria University of Wellington, New Zealand, and is published three times a year. Joint Editors:
Like the New Zealand terrestrial vertebrate fauna as a whole, the fresh-water fish fauna of New Zealand is not large, as only six or seven families of fresh-water fish are native to New Zealand.
About 35 New Zealand species of fresh-water fish are at present recognised. These comprise 17 species of the family Galaxiidae in two genera (Neochanna, two species and Galaxias, 15 species); six species in the family Eleotridae in two genera (Gobiomorphus, four species and Philypnodon, two species); two species of Anguilla in the family Anguillidae; one species (which may be extinct) of Prototroctes (family Aplochitonidae); one species of Cheimarrichthys (family Cheimarrichthyidae); one lamprey Geotria, family Geotridae); one flatfish (Rhombosolea, family Pleuronectidae), which enters and lives freely in the sea and is a doubtful member of the fresh-water fauna.
Of these fishes all but one species of Galaxias (G. attenuatus), one eel (Anguilla australis) and the lamprey (Geotria australis) are endemic, although all the genera except Neochanna and Cheimarrichthys are shared with other regions. The family Cheimarrichthyidae, comprising only one species, is confined to New Zealand. About 92% of the species but only 11% of the genera in the fauna are thus endemic to New Zealand, indicating a relatively young fauna and/or incomplete faunal isolation from other regions. The high endemism at species level indicates that the fauna has been isolated in recent times but the generic similarities suggest that the fauna is not of great age.
The New Zealand fresh-water fish fauna contains two elements:— 1. Temporary inhabitants of fresh-water, either anadromous or catadromous; 2. Permanent inhabitants of fresh-water. Most of the taxonomic groups in the fresh-water fauna have representatives in the first of these groups. Galaxias attenuatus breeds in estuarine conditions after maturing in the rivers, and the larval life and much of the juvenile life is spent in the sea. Prototroctes oxyrhynchus is thought by some authors to have behaved similarly (e.g. Arthur, 1884, p. 172). Gobiomorphus huttoni breeds in fresh-water but larval life is thought to be marine and this may apply to other New Zealand Eleotridae. The breeding place of Cheimarrichthys forsteri is undescribed and larval C. forsteri have not been found, although large adults full of eggs have been taken in autumn. Both species of Anguilla have marine breeding and larval life. Anadromous, partially fresh-water dwelling species include those species of Retropinna which are not entirely fresh-water dwelling (R. retropinna, R. osmeroides, R. anisodon) and which enter estuaries and lowland streams from the sea to breed; Geotria australis behaves similarly and Gobiomorphus basalis may be anadromous but is more usually resident in fresh-water. The permanent inhabitants of fresh-water show varying migratory patterns, where these are known.
As outlined above, 92% of the species but only 11% of the genera of New Zealand's fresh-water fishes are endemic to New Zealand. Generic relationships are widespread, but mostly confined to the Southern Hemisphere.
Galaxias, using this name in a broad sense to include Paragalaxias and Saxilaga, etc., is distributed as follows:— Australia (about 27spp.), New Caledonia (1sp.), New Zealand (16spp. with one species on the Campbell and Auckland Islands), South America and the Falkland Islands (10spp.) and South Africa (2spp.). At the species level, each area comprises only endemic species except for the presence of Galaxias attenuatus in south-east Australia, New Zealand and South America (including the Falkland Islands).
The genus Retropinna is found only in the Australasian region, the six New Zealand and three Australian species being endemic to each area. Anguilla is a cosmopolitan genus with one species endemic to New Zealand and the other New Zealand species also present on New Caledonia and the south-east of Australia. The family Aplochitonidae is represented by one species of Lovettia from Tasmania, one species of Prototroctes from south-east Australia and Tasmania and another species from New Zealand, and the genus Aplochiton from South America. Geotria is a
Geotria australis occurs in south-west and south-east Australia, Tasmania, New Zealand and Chile. Cheimarrichthys belongs to an endemic, monotypic family of uncertain relationships. Affinity has been suggested with the Indo-Pacific Parapercidae, but this relationship has not been studied and remains in doubt.
The family Eleotridae is a large Indo-Pacific family of which the New Zealand species comprise the southernmost extension. The two genera present in New Zealand (Gobiomorphus, four species, Philypnodon, two species) are also present in south-east Australia where there is one species in each genus. The species in each area are endemic.
On the basis of existing distribution, it is apparent that the affinities of the New Zealand fresh-water fish fauna are southern, mostly with Australia but also with South America. Affinities with the South African fauna occur but are not marked.
Fleming (1962, p. 152) dates the latest possible land connection between Australia and New Zealand as Cretaceous. Earliest fossil Isospondyli are Jurassic, so that it is possible that some groups of fresh-water fishes could have reached New Zealand by land routes. The only fossil traces of fresh-water fishes known in New Zealand are Pliocene (Stokell, 1945, p. 134), and fossil evidence is thus largely lacking. Postulated land connections between Australia and New Zealand are through the Lord Howe Ridge to the north-west of New Zealand connecting with either New Guinea or Queensland, but the New Zealand-Australian fresh-water fish relationships are most marked between south-east Australia and New Zealand. Use of a postulated land bridge for distribution of fish between Australia and New Zealand would mean that the fish groups involved must have had wider distribution to the north in Australia in Jurassic-Cretaceous times. As the Cretaceous was a period of marked cooling (Fleming, loc. cit.), it is possible that this was the case. Apart from the uncertainty of the existence and duration of such a land bridge, the establishment and use of fresh-water routes along the bridge also remains questionable. As suggested below, the use of such a bridge is not essential. The lack of affinities with the bulk of the South American fresh-water fish fauna indicates that the New Zealand fishes did not reach New Zealand from South America by land routes. New Zealand lacks all the primitive and primary fresh-water fish groups (e.g. the Ostariophysi) which abound in South America, and these groups are also mostly lacking from Australia. The general concensus of opinion (e.g. Simpson 1941, Stokell 1950, 1953, Myers 1953) gives no support for the older ideas of Gill (1893) and Oliver
Geotria, with marine adult existence and its habit of attaching itself to fishes poses no problem of distribution. Similarly, the arrival of the two eel species in New Zealand is simply explained by transportation of their leptocephali in ocean currents and there is no problem of distribution mechanism. Cheimarrichthys forsteri seems to be a recent local marine derivative. The groups in which derivation and dispersal are less clearly indicated are the Retropinnidae, Aplochitonidae, Galaxiidae and also the Eleotridae.
The Eleotridae in New Zealand are representatives of a wide-ranging Indo-Pacific group of marine and estuarine species, which invade fresh-water in most regions. The closest relationships of the New Zealand eleotrids appear to be with Australia, as both genera present in New Zealand also occur in Australia. The presence of the two genera in both Australia and New Zealand implies double invasion or convergent evolution within the group in the two regions. Contemporary authorities on the Eleotridae in New Zealand (e.g. Stokell, 1959) consider the separation of the New Zealand Eleotridae into two genera unnatural, and that the New Zealand Eleotridae are more closely allied to each other than to the Australian species of each genus. Present opinion tends to favour the view that all the New Zealand freshwater Eleotridae should be included in one genus (Gobiomorphus) and that this group has probably arrived in New Zealand only once. That they did arrive in New Zealand and did not originate here and spread to the north is quite clear from the greater numbers and diversification of the Eleotridae in the tropics to the north-west of New Zealand. The New Zealand fauna is poor in eleotrid species and none are known any further south than New Zealand. The Australian species of Gobiomorphus (G. coxii) is similar to the New Zealand species and is probably closely related. No local marine species of Eleotridae indicate close generic relationship to Gobiomorphus.
The family Retropinnidae is confined to the Australasian region, with three Australian species and six species in New Zealand. Distribution of the family is south-east Australia, Tasmania, New Zealand. Australian species are anadromous, breeding in fresh-water, and three New Zealand species have similar habits, but the other three species are entirely fresh-water dwelling.
The family Aplochitonidae is represented by two species in Australia (one species each of Lovettia and Prototroctes), a species of Prototroctes in New Zealand and the genus Aplochiton in South America and the Falkland Islands. The New Zealand species of Prototroctes is thought to be catadromous with marine larval
Lovettia seali in Tasmania and Aplochiton marinus in South America both have marine stages in their life histories. Prototroctes in Australia is present in the south-east and in Tasmania.
Finally the Galaxiidae are present on all the southern land masses, and show greatest diversification in Australia (27 spp.) with reduction in the numbers of species towards the east (New Zealand 17 spp., South America and the Falkland Islands 10 spp., South Africa 2 spp.). The pattern of numerical distribution suggests origin of the group in the west, with eastward distribution in the west wind drift from Australia to New Zealand, South America, and South Africa. Except for the presence of Galaxias attenuatus in south-east Australia, New Zealand and South America, species in each area are distinct.
In the above discussion it is readily noticeable that when there are affinities between Australia and New Zealand, the distribution pattern is south-east Australia, sometimes Tasmania, and New Zealand. This pattern applies to the three species in common (Galaxias attenuatus, Anguilla australis and Geotria australis) and to the genera Gobiomorphus, Philypnodon, Prototroctes and Retropinna; in other words, almost all the groups which the author suggests have been derived from other than local marine species. There is thus a common pattern for these groups: viz. south-east Australia, perhaps Tasmania, and New Zealand, with the Geotridae and Aplochitonidae extending further east to South America, and the Galaxiidae present in both South America and South Africa. What is the centre of distribution and means of dispersal of the New Zealand fresh-water fish fauna?
In view of the improbability that the New Zealand fresh-water fish fauna used a land migration route, varying suggestions of derivation and dispersal must be examined. Allen (1956) presents the possibilities as follows: (1) Marine ancestry common to the groups in each area, the ancestors now no longer living; (2) Transoceanic migration of fresh-water forms which are euryhaline; (3) Parallel or convergent evolution of the groups in the different regions.
To hypothesise parallel evolution within the Galaxiidae, Aplochitonidae and Retropinnidae is unreasonable. To do so for one of these groups is less unreasonable, but this leaves the derivation and dispersal of the other two groups to be explained. If an explanation can be offered for the derivation of these other two groups, it is probable that the same reasoning would apply to the group for which parallel evolution is postulated. That three groups should evolve convergently in two, three or even four widely separated areas, all from unknown ancestry, is unlikely.
There is no evidence for or against a common marine ancestry for the groups under discussion, and no recent marine ancestors
The third alternative is that euryhaline species have been distributed from their centres of origin by ocean currents or active migration. Both Myers (1938) and Darlington (1957) place all the families of fishes discussed in this paper in the peripheral fresh-water group (i.e. fishes with high salt tolerances) and most groups are found to have representatives which breed in the sea or have some stage of the life history which is marine. That such fresh-water fishes can be distributed across large ocean gaps is indicated by the presence of Galaxias attenuatus in Australia, New Zealand and South America, with little chance that this species was transported by other than ocean currents. Further support for transoceanic dispersal of fresh-water fish to New Zealand is the faunal relationship between south-east Australia (Tasmania) and New Zealand outlined above, and the presence of the warm east-Australian (Notonectian) sea current which impinges on much of the west coast of New Zealand. It is this current which is thought to carry the leptocephali of the New Zealand eel, Anguilla australis, each year from a more northern breeding site across the Tasman Sea. In view of the known ability of Gobiomorphus huttoni, Philypnodon hubbsi, Galaxias attenuatus, Retropinna spp., Anguilla spp., and Geotria spp. to tolerate sea water it is suggested that the fresh-water fish fauna of New Zealand has been derived from the north-west, mostly from Australia, by transportation in the east-Australian current. All the fishes concerned except the Eleotridae are free-swimming pelagic-type fishes and what is known of the life histories of the Eleotridae suggests that some of these have marine pelagic larvae.
Derivation of the New Zealand fresh-water fish fauna by ocean current dispersal across sea gaps seems preferable to the derivation of at least four groups in widely separate areas, each group from an unknown and/or extinct marine ancestor. The numerical distribution of the Galaxiidae strongly supports dispersal from the west with origin in Australia, and in the lack of evidence of movement in the opposite direction, there is no reason to postulate the reverse movement.
The wide-ranging to circum-polar distribution pattern seen in the Galaxidae, Aplochitonidae, Geotridae and to a lesser extent the Retropinnidae, parallels the situation seen in the Salmonidae,
The fresh-water fish fauna of New Zealand has been derived mostly from Australia by transoceanic dispersal of larval or adult fishes. Earlier arrivals were probably the more primitive Isospondyli — the Galaxiidae, Retropinnidae and Aplochitonidae — with the Eleotridae arriving more recently. A further emigration of Galaxiidae is suggested by the distribution pattern for Galaxias attenuatus. The distribution of G. attenuatus clearly shows that transoceanic dispersal can disperse fishes across the South Pacific Ocean to South America. This mechanism probably accounts for the fresh-water fish faunal relationships between Australasia and South America.
As Myers (1953) has said, there is nothing in the New Zealand fresh-water fish fauna to indicate land connections; the ‘key to relationships is marine wandering.
I wish to express my thanks to Mr.
The New Zealand flora exhibits a number of unusual features and notable among these is the relatively high proportion of flowering species having unisexual flowers. Not all species have been fully investigated, but Millener (1961) has estimated that about 25% exhibit unisexuality in New Zealand compared with only 8% in the British flora. The contrast becomes even more striking when certain cosmopolitan genera and families are singled out for consideration. In Clematis, for instance, the New Zealand species are dioecious (male and female plants), while elsewhere in the world this sexual pattern is so uncommon in the genus that a European species possessing it has the name Clematis dioica. Rubus in New Zealand is a similar case.
Among families unisexuality is prevalent in the New Zealand Umbelliferae. In this family elsewhere in the world flowers are predominately hermaphrodite, although in some cases male flowers may be mixed with hermaphrodite in the same inflorescence. Of the 94 species currently recognised for the family in New Zealand, at least 54 (58%) are dioecious (Anisotome, Aciphylla, Coxella), probably 8 (8%) are gynodioecious i.e. with female and hermaphrodite plants (Gingidium), and 32 (34%) are hermaphrodite (Daucus, Apium, Lilaeopsis, Oreomyrrhis, Eryngium, Hemiphues, Centella, Hydrocotyle, Schizeilema). In New Zealand unisexual flowers apparently occur only in the subfamily Apioideae for which 72 native species are recognised. The corresponding percentages for the subfamily are 76% dioecious, 10% gynodioecious and only 14% hermaphrodite. Eight of the 14 genera of the Umbelliferae in New Zealand belong to the subfamily Apioideae and of these 4 genera (Anisotome, Aciphylla, Coxella, Gingidium) exhibit unisexuality.
Unisexuality then is a common condition in the New Zealand Umbelliferae and it is also relatively common in the New Zealand
During the Pleistocene the climate fluctuated widely and there must have been a high rate of extinction at some times and a high rate of speciation at others. Possibly the dioecious element in the New Zealand flora began to expand at this time.
Recently while transferring a preserved wandering sea-anemone, Phlyctenactis sp. (prob. P. tuberculosa), to a more suitable container, I felt a hard object within the animal. This proved to be a bivalve mollusc, Longamactra elongata, and apparently had been engulfed by the anemone as food. The mollusc was slightly agape but intact. Seemingly it had been taken by the anemone just before the latter itself was captured in the fishing trawl. The anemone, in the contracted state of preservation, is 8 × 6 cm. while the shell is 6 × 4 cm. The typical hieroglyphic markings on the epidermis of the L. elongata are unimpaired. As many undamaged but empty shells of L. elongata are taken in the region it may well be suspected that they are regurgitated by this predator. The specimen was taken in 15-18 fathoms, E.S.E. of Oamaru, in July, 1960, and this is the greatest depth in which I have noted the wandering sea-anemone.
This is the first of a series of articles in which it is intended to review the more important introduced ungulates. Each article will deal with one species and include its systematic position, description, present distribution, history of introduction, subsequent dispersal and present economic position in New Zealand.
The Himalayan Tahr was introduced to New Zealand some 60 years ago primarily for the purposes of sport. Apart from a small herd in England this was the first time tahr had been liberated outside their native range, but they quickly adapted themselves to their new home and their numbers increased rapidly. Although they have not dispersed as far as chamois, which were liberated in the same area a little later, tahr occupy an important part of the Southern Alps, extending from the Landsborough River in the south to the Waimakariri River in the north. Prized as a trophy by sportsmen, tahr have nevertheless increased to such an extent as to cause damage to the alpine flora, resulting in increased erosion and soil loss. Since 1937, attempts have been made to control them, initially by shooting and later by poisoning.
Simpson (1945) placed the Tahr in the Order Artiodactyla, Family Bovidae, Subfamily Caprinae. He divided the Subfamily Caprinae into four tribes with the genus Hemitragus Hodgson, 1841 placed in the Tribe Caprini.
Three species of Hemitragus are recognised: Hemitragus jemlahicus (Smith, 1827) (Himalayan Tahr); H. jayakari Thomas, 1894 (Arabian Tahr); and H. hylocrius Ogilby, 1837 (Nilgiri Tahr).
Hemitragus jemlahicus is in turn divided into two sub-species: H. jemlahicus jemlahicus (Smith, 1827), and H. jemlahicus schaeferi Pohle, 1944.
Further, H. jayakari seems to be closely related to H. jemlahicus and could possibly be regarded as a sub-species of it (Ellerman and Morrison-Scott, 1951).
There are two different spellings of the specific name in use. Some authors (e.g. Donne, 1924; Wodzicki, 1950; Riney, 1955) use the form jemlaicus. Others, (Lydekker, 1913; Simpson, 1945; Ellerman and Morrison-Scott, 1951) refer to the specific name as jemlahicus. However, H. jemlahicus was first described by Smith under the name Capra jemlahicus Smith, 1827 (although printed correctly under the plate it was misprinted jemlanica in the text), and thus the spelling jemlahicus is the correct form. The specific name is taken from the Jemla Valley, north of Nepal. The incorrect spelling, jemlaicus, dates from Gray (1847).
The common name of H. jemlahicus varies considerably, including Tehr, Tahir, Jharal, Jehr, Jula Kras and Thar or Tahr. Although Riney (1955) and Anderson and Henderson (1961) use the name ‘Thar’ most authors refer to it as the Himalayan Tahr or just Tahr (Lydekker, 1913; Wodzicki, 1950; Ellerman and Morrison-Scott, 1951; Bourliére, 1955). Banwell (1962) concludes after some research that ‘tahr’ is correct.
The animals are similar in appearance to large goats, with adult males measuring up to 40 inches at shoulder height. Occasional mature adult males are over 300lb, while mature adult females weigh much less, seldom more than 80lb. The face is long, narrow and straight. The head of an adult male is short-haired while the body-hair is long, particularly on the neck and forequarters, and forms a mane almost to the knees. The hair of the female is much shorter and generally similar to that of the domestic goat. The under side of the tail is bare, and the knees and chest often have callous pads. The colour is reddish or dark brown, usually darker in males. The mane is often lighter in colour than the rest of the body-hair, especially towards the end of the winter. A more or less distinct dark dorsal stripe is present. Young animals are more uniform in their colouring, which is greyish brown, and kids are considerably lighter than the adults (see Figs, 1 and 2).
Face glands and foot glands are usually absent, although vestiges of the foot glands in the hind feet occasionally occur. The inguinal gland is also absent but a nuchal gland is present (Davidson, 1963). There are four teats present but, contrary to Riney (1955), only the posterior pair appear to be functional (Anderson and Henderson, 1961).
Horns, present in both sexes, are slightly larger in males than females. The horns nearly touch at the base, curve and diverge backwards, and approach again at the tips. They are compressed,
The hooves are particularly well adapted to rough terrain. The pad is soft and slightly convex, and is surrounded by a hard rim. This is similar to the hoof of the chamois (Rupicapra rupicapra) which occupies similar terrain to the tahr, but differs from that of the mountain goat (Oreamnos americanus) in which the hard rim is shorter, the pliable convex pad extending beyond the hard outside edge (Brandborg, 1955).
The tahr's senses of smell and hearing are both well developed but, like the chamois, tahr appear to rely more on their exceptional eyesight. The voice is a high-pitched whistle used only for alarm calls. Young kids bleat occasionally, in a similar fashion to chamois kids.
The distribution of the genus Hemitragus includes the ranges of the Himalayas, the Nilgiri, Anamalais, Western Ghats and some other south Indian ranges, and the mountains of south-eastern Arabia.
The Himalayan Tahr is found in the middle ranges of the Himalayas from Pir Punjal mountains, Kashmir, Punjab, Kumaon, Nepal and Sikkim. The type locality is the Jemla Hills, Nepal. Tahr inhabit rough rocky ranges up to 14,000 feet (Donne, 1924), although Bourlière (1955) states that they live by preference in the forest and rocky places under 10,000 feet.
There are only a few herds outside their native habitat including: the New Zealand herd; a herd of about 30 animals at Woburn, England; and a herd of about 50 living on Table Mountain, South Africa, the progeny of animals which escaped from the Pretoria Zoo some 30 years ago.
In 1904 the Duke of Bedford gave the New Zealand Government six tahr selected from his herd at Woburn. Donne (1924) records that the Duke intended to send eight animals but two escaped just prior to shipment. These six tahr, three of each sex (although in an appendix Donne states that there were 2 males and 4 females) left England in April, 1904, and reached Wellington by the end of May. During the voyage one male escaped and was lost overboard but the remainder were in good condition when they arrived, and after a quarantine period were liberated in the Mt. Cook area. In 1909 the Duke of Bedford presented New Zealand with a further eight tahr (six male and two female) and these animals were also released near Mt. Cook. Donne (1924) records that three more (adult male, female and a young female)
Tahr quickly became acclimatised and by 1913 were recorded in numbers on the Sealey Range and by 1918 in the main range (Thomson, 1922).
Tahr have dispersed from their liberation point to occupy a substantial part of the Southern Alps, as shown in Fig. 3. At present a continuous population extends from the Hopkins Valley in the south to the Wilberforce Valley in the north. There are a number of occurrences of tahr outside the boundaries (Fig. 3), but these are usually wandering bulls and do not give a true indication of the main population distribution. Caughley (1963), in discussing dispersal rates of several of the introduced ungulates, reports that tahr spread from their liberation point at the rate of 1.1 miles per year. Of the dispersal rates of the nine species listed by Caughley, tahr have the second fastest, being exceeded only by chamois.
For most of the year the bulls (adult males) usually mob together living apart from the nanny herds (adult females, immature bulls and kids). The sexes mix during the rut (end of April, May and June) when the bulls pair off with mature nannies — the relationship, in general, is monogamous. After the rut, the distribution is determined by snow, which is lower at this time of year. Tahr descend and seek the cover of rocky outcrops and other sheltered places in bad weather. As the weather improves in spring the herds gradually make their way back up to the summer pastures.
Young are usually born in December. Asdell (1946) reports that tahr in their native habitat rut during December, and young are usually born the following June or July, with a gestation period of 180 days, whereas Anderson and Henderson (1961) for the New Zealand tahr give approximately 220 days. Usually only one young is born, but there have been reports of twinning (Anderson and Henderson, 1961). Tahr do not live much more than 20 years in captivity, and in the wild probably considerably less. Anderson and Henderson estimate that 80% of all young die by the end of their third winter. No predators of tahr other than man occur in New Zealand, but a number of deaths are probably due to accidents owing to the extremely rugged terrain which tahr occupy.
Chamois and, less commonly, tahr have been found diseased or blind in the Southern Alps. One cause is pinkeye (Kerato-conjunctivitis); the eyes become white and the disease causes
Contagious ecthyma (scabby mouth), also found in chamois and sheep, afflicts tahr in New Zealand. Symptoms include festering wounds and scabs on the mouth, palate, udders and feet. It first appeared among the tahr herds in the Murchison Valley area in 1940, and has since been recorded amongst tahr in the Mt. Cook area in 1943, Ben Ohau Range in 1959, and the Upper Rangitata in 1961 (Daniel and Christie, 1963).
The total effect of these diseases on tahr populations is probably light. Generally the severity of the diseases seems less amongst tahr than amongst chamois although no data have been collected to substantiate this.
Tahr carry a small host-specific mallophagan louse (Damalinia hemitragi). Cummings (1916) first described the female louse from a tahr in the gardens of the Zoological Society of London, and both male and female have been recorded from tahr in New Zealand (Andrews, MS.). No further records are known to the writers.
Nematode parasites recorded from the tahr are: Oesophagastomum venulosum and Trichuris ovis (the whipworm) from the caecum, and trichostrongylids from the abomasum and small intestine. Both O. venulosum and T. ovis also occur in sheep, some of which were present in the area (Godley Valley) where these parasites were found in tahr.
The Animals Protection and Game Act, 1921-22, lists tahr as a protected animal but this protection was removed in 1930 because of the apparent damage caused by these animals on the vegetation. It was not until 1937 that the first Government operation against tahr was conducted, 2,765 animals being killed. Government operations against tahr have been undertaken almost every year since then and over 24,500 animals have been killed by shooting. In 1960, the first poisoning operation against tahr was carried out in the Tasman watershed using sodium monofluoroacetate (compound 1080). Private shooters have killed an unknown number of tahr since protection was removed.
Apart from being a trophy animal for sportsmen, tahr have virtually no economic value; only a few animals are skinned, and opinions vary as to the palatability of the meat, ranging from excellent (Anderson and Henderson, 1961) to that of Colonel Markham (quoted in Jerdon, 1874) who states ‘The flesh of the female is tolerable; that of the male scarcely eatable at any time’.
Many scientists today are noticing and rejoicing that the ‘separate disciplines’ of science are tending to merge or at least to overlap. This very desirable movement is clearly seen (and is extremely important) in the relationship between Chemistry and Biology.
Only a few decades ago, chemists mostly regarded living things as bewildering sources of an inexhaustible fund of strange compounds, and as possible cheats in the game of physical chemistry. Biologists were still largely occupied with classification, and of the few who asked the question ‘What chemical changes are going on in these living cells?’, most despaired of there being any answer obtainable by scientific investigation.
Today things are different. The catalogue of chemicals which occur in cells seems largely complete, and good progress has been made towards following the processes whereby food is built up into an organism's own substance, or burnt as fuel.
One outstanding discovery has been the ubiquitous biochemical known familiarly as ATP. This compound seems to be of immense importance in the workings of organisms. It is in fact a ‘portable power-pack’, assembled at a few special factories in a cell and carried about all over the other parts for use as a source of energy in mechanical or chemical operations.
‘ATP’ stands for ‘adenosine triphosphate’. Its molecular structure is:
The non-chemist need not take fright and flee from either the name or the formula! For our present purposes, we can represent the molecule quite simply with this equivalent picture:
A — (P) — (P) — (P)
The complexities of the ‘A’ part (adenosine) need not concern us: attention should be focussed on the string of three phosphate units, each drawn as (P), which give rise to the epithet ‘triphosphate’.
Now the main point to grasp is that when the end (P) is split off, so:
The splitting of ADP, leaving the monophosphate AMP, is also very exergonic.
This energy is used to drive end-ergonic reactions, i.e. those which must absorb energy if they are to proceed. Now cells abound with endergonic reactions — for making proteins, starch, nucleic acids and many other essential substances. ATP is used as a source of energy to drive along these reactions.
Some people get the idea that the way this works involves merely ‘letting off an ATP squib’ in the vicinity of some recalcitrant compound which is thereby somehow hustled along and undergoes the desired endergonic reaction in double-quick time. This is quite wrong. To give an example of how ATP is in fact used to make such reactions go, let us take the joining of two simple sugars, glucose and fructose, to form the ‘double sugar’ sucrose. What happens is actually a ‘coupling’, or gearing together of the two reactions
H2O + ATP = ADP + (P) (1)
glucose + fructose = sucrose + H2O (2)
These reactions (1) and (2) are not simply conducted in the same vicinity. The actual reactions which occur are:
glucose + ATP = glucose—(P) + ADP (3)
and then glucose (P) + fructose = sucrose + (P) (4)
Although (1) and (2) add up to the same nett reaction as (3) and (4), they do not in fact represent the true process.
Many different compounds needed by a living cell are built up in a comparable way.
ATP is thought also to provide the energy for muscular work, for bioluminescence, for absorption and secretion and for generation of high voltages. It has been known for about 30 years that ATP is used in the action of muscle; but just how its stored energy is converted to mechanical work is not understood, though dozens of theories have been suggested.
How does a cell assemble this energy bundle? Exactly as much energy as is given off when ATP is split must be supplied to form ATP from ADP and free phosphate. A cell's energy comes from oxidising food, usually to carbon dioxide; and green plants have the additional resource of trapping sunlight and using its energy for their own chemical needs. Both these processes, respiration and photosynthesis, are so arranged in the cell See ‘Mitochondria’ and ‘Chloroplasts’ in ‘The Cytoplasm of Plant Cells’, Tuatara 11 143 (1963).
Here we have seen one example of what can be gained by applying knowledge and methods from one ‘;separate discipline’ of science to problems which had been considered to belong in another sphere. Biologists need not think that the movement of overlapping is one-way. At least some chemists are predicting that biologists will help tackle chemical problems a good deal more in the future than they do now; and of course their present aid is quite considerable. A good deal of specialisation in our studies is no doubt necessary, but it should not be allowed to put blinkers on our scientific outlook.
The chromosomes of the cell nucleus, and mitosis, the process of cell division, are apt to dominate one's thinking when confronted with the term ‘cytology’. This is by no means the fault of the reader or hearer alone for before the advent of the electron microscope cytologists were largely engaged in a study of chromosomes; the cytoplasm was often regarded as having little if anything new to offer its investigators. The reason of course was that the resolving power of the ordinary light microscope was limiting. It was not until the discovery of the electron microscope less than 20 years ago that a break-through came and careful attention was turned again to other-than-nuclear structures. To the cytologist the electron microscope increased resolution beyond belief bringing startling new fields for research into discernment of the human eye. Today the balance is tipped, and the cell cytoplasm with its now revealed array of organelles and membrane structures is the centre of attention of many cytologists. In fact the chromosomes of the nucleus are often looked on as too large for the electron microscope, and it is only very recently that electron microscopists have begun looking anew at these unique structures.
In respect of new discoveries mention must be made too of the great contributions that phase-contrast and birefringence microscopes, and the use of radiography have recently given cytology. To be able not only to see various components in a living cell but also to ‘see’ certain molecules in this cell and to follow others in their cellular passage and metabolism has been of tremendous importance.
‘Cytology’ from the Greek Kutos meaning ‘a vessel’ is the study of cells. Karyology is a specialised branch of cytology dealing with the cell nucleus. This branch of science is over a century old. Since the nucleus was discovered by Tuatara.
Nearly all living cells possess a nucleus, for this body is the controlling centre, the ‘brain’, of the whole cell. A few living cells such as human red blood corpuscles have no nucleus. These, however, are very specialised cells; their nuclear loss during differentiation of a specialised structure and function is parallelled by a loss of nearly all the major functions of protoplasm. More correctly, perhaps, it should be said that most cells possess nuclear material, for a number of organisms are devoid of the distinct structure we generally associate with the term nucleus. Bacteria, for instance, have a less dense core (under the electron microscope) of material surrounded by a jacket of cytoplasm; the core is the nuclear material and may be equated with chromatin, the major functional and structural component of nuclei in general. Viruses (not strictly cells) consist simply of nuclear material surrounded by a protein coat.
With a microscope, a slide and a coverslip it is easy to see, if only to see, a cell nucleus. With your fingernail scrape a portion
The living nucleus cannot always be seen as easily as those of palatal epithelial cells, for the nucleus commonly exhibits optical properties identical with those of the cytoplasm. Under the phase-contrast microscope, however, particularly at a time when the cell is preparing to divide, the living nucleus is readily visible. This fact has enabled important comparisons to be made with stained material, and these comparisons have shown that careful fixation and staining give a reasonably clear and correct representation of the internal structure of the nucleus.
The form of the nucleus is generally ovoid (Fig. 1) though various diverse shapes arise in cells with specialised metabolic functions. Larval insects, for example, have much branched nuclei in their cocoon spinning gland cells.
There may also be more nuclei in a cell than the usual one. Multinucleate organisms as some fungi and algae and most voluntary muscle cells have many nuclei distributed throughout their cytoplasm. The giant amoeba Chaos has many nuclei in its single cell, while such unicellular ciliates as Paramecium commonly have a large macronucleus and a number of small micronuclei. Human red blood cells we have already noted are enucleate. The number of nuclei possessed by a cell is probably closely related to the mass of surrounding protoplasm, since within certain limits a definite nuclear surface area: cytoplasmic volume ratio must be maintained for continued functioning of the cell as a whole.
The position of the nucleus is quite variable and is largely determined by the physical features of its surrounding cytoplasm. In a young cell it ordinarily occupies the centre of the cell (Fig. 1), but as the cell becomes vacuolated during differentiation it is commonly displaced, with the cytoplasm, to the side of the cell. Position is possibly related to function for it often lies in regions of high metabolic activity.
A nucleus not visibly undergoing division is referred to as a resting, interphase or metabolic nucleus. The term ‘resting’ implies inactivity, at least as far as cell division is concerned: in dealing with mitosis in the following article it will be clearly shown that this is not true; the ‘resting’ nucleus is indeed very actively associated with division. The term ‘interphase’ is descriptive though suggestive of a phase in which only certain features of cell division occur. This is true in some respects for we know today that ‘interphase’ is the principal stage of reproduction rather than division. The term ‘metabolic’ suggests that this phase is one of major metabolic activity in the nucleus.
The combined term ‘interphase-metabolic’ used here refers to the nucleus of a young (meristematic) cell as distinct from that of a differentiated cell. The latter, though metabolic, (as above) appears incapable of normally entering division and, therefore, is not strictly interphasic.
Cells which have been appropriately killed (fixed) and stained show the nucleus to be composed principally of two phases, a nucleoprotein or chromatin phase dispersed throughout an essentially protein mass, the nucleoplasmic phase. The chromatin is generally responsible for the staining properties of the nucleus and imparts to it affinities for a wide variety of dyes. One of these dyes, a very important one, is basic fuchsin (Feulgen's stain); it is specific for deoxyribonucleic acid (DNA), the main acid portion of chromatin and that portion now known to be the hereditary material of an individual. The specificity of the dye has enabled research workers to make accurate estimates of the quantity of DNA in a particular cell; the results obtained were an important early pointer to the identification of this acid portion of chromatin as the carrier of genetic information.
During the early stages of nuclear division the chromatin of the metabolic nucleus becomes transformed into a fixed number of individualistic bodies. These are the chromosomes (Figs. 4-7). Also within the nucleus, one or two (sometimes more) rather large, deeply staining bodies known as nucleoli can usually be seen (Fig. 1). These bodies are formed at particular regions of the chromatin and it is probably best to regard these organelles as specialised portions (with specialised functions) of the chromatin phase.
The nucleus is bounded from the cytoplasm by a nuclear membrane.
The electron microscope has been very useful in revealing the finer morphology of the nuclear membrane (nuclear envelope) (Fig. 2) and has given at least an indication of how it is formed after the nucleus has divided. Indications are that the membrane is a specialised cytoplasmic structure, and it was therefore described in detail in an earlier article in this series (Sampson, Tuatara 11/3). Apart from morphology, however, the puzzling question of its
The nucleolus (Figs. 1, 2 and 3) is often the only conspicuous organelle in the living meristematic cell. This fact led to the early discovery and description of the nucleolus as a major component of the nucleus.
When stained nearly all nuclei show the presence of one or a few nucleoli. The actual number depends not only on the species, but on the metabolic activity of the cell as well, for while the number is generally constant in meristematic cells, nucleolar fusion or budding paralleling differentiation and metabolic activity may considerably alter this number. In young cells where modification in number has not occurred this basic number of nucleoli is an indication of the number of sets (see later) of chromosomes present in the cell, and also a reflection on the mode of formation of the nucleolus. The nucleolus disappears (perhaps more correctly, disperses) at the earliest phases of cell division and is reformed (reorganises) in the closing phases. Reformation takes place at specialised regions on certain chromosomes of the complement (Fig. 3). The number of these so called organising chromosomes is constant under normal conditions and hence so is the number of nucleoli formed.
Under the electron microscope the nucleolus is seen as an aggregation of electron dense granules (Fig. 3). The granules are considered to be composed of ribonucleoprotein (i.e. protein plus ribonucleic acid). There is no membrane forming a boundary between the nucleolus and the remainder of the nucleus.
Electron micrograph studies on nucleolar formation have revealed that nucleolar material (prenucleolar bodies) first appear as ribonucleic (RNA) or RNA-protein granules scattered amongst
The precise origin of the prenucleolar bodies is still rather obscure, though it seems probable that the RNA of these bodies is produced from special loci on the chromosomes, and that their protein portion is derived from pre-existing proteins of the cell, formed before division. During organisation, RNA replication and nucleolar RNA synthesis of protein probably account for nucleolar growth.
Chemically, nucleoli have a very high content of protein with up to 6% RNA. This RNA content is 90% of the total RNA of the cell as a whole. Autoradiographic studies have shown that there is a constant turnover in nucleolus RNA (i.e. RNA is constantly being formed and then used). There is also an incorporation of amino acids into proteins as a result of nucleolar activity.
Quite dramatic progress in recent years has been made towards understanding the function of the nucleolus and its relationship to the cell as a whole. Many functions have hitherto been attributed to the nucleolus. To mention a few, the organelle was once considered to be of no functional use to the cell at all and was bound for eventual loss. Almost as an antithesis it was considered at one time to be the progenitor of the nucleus and hence of the cell as a whole. Other suggested functions included one as a food store for the nucleus, another as responsible agent of numerous activities of the nucleus during its division. A number of earlier workers, however, realised that a direct relationship existed between cellular metabolism and nucleolar activity. Thus protein synthesising embryonic cells, meristematic cells and specialised secretory cells characteristically have very large nucleoli (Fig. 1); differentiated cells reverting to a meristematic condition to repair damaged tissue show conspicuous enlargements of nucleoli; starved cells have smaller nucleoli than normal, and refeeding these cells causes the nucleoli to revert to normal size. Even before it was clearly realised that the nucleolus is associated with protein synthesis, these observations led to the suggestion that cancerous growth might be caused through a disruption of nucleolar controlled metabolism leading to an excessive production of cellular material, and hence to malignancy. Many cancerous cells have very large nucleoli. This hypothesis has by no means been proved but it is still a currently held view of some carcinologists. What might cause an over activation of nucleolar functioning presents the problem. Viral infection, chemical substances (smoking?), various radiations (atom bombs?) and other mutagenic agents are all known to affect in diverse ways the morphology of nucleoli and the synthesis of cytoplasmic proteins. The alternative, and the most commonly held explanation for the nucleolus/cancer relationship, is that disturbed metabolic activity in the cytoplasm affects nucleolar activity. In this view the root cause of cancer is to be found elsewhere in the cell rather than in the nucleolus.
The identification of a constant turnover of RNA in the nucleolus has given strong experimental support for the present day concept that the nucleolus is the site of synthesis of a major portion at least of cytoplasmic RNA, and is closely associated with cytoplasmic protein synthesis.
Of what importance to a cell is cytoplasmic RNA?
There are three major types of RNA present in a cell, distinguishable by their function, their site of synthesis, whether or not they are end products in themselves, and sometimes in their chemical make-up. Firstly, ‘structural’ or ‘particulate’ RNA is built into the framework of cytoplasmic organelles (e.g. ribosomes). ‘Carrier’ or ‘transfer’ RNA is not an end product
Later a little more will be said concerning this protein synthesising mechanism. Its importance will be seen when it is understood that enzymes are proteins, that enzymes control metabolic activities of a cell, and that these activities ultimately control the very form a cell is to assume.
Autoradiography, particularly in sea-urchin eggs and certain dipterous salivary gland cells, has shown that a major portion of cytoplasmic tranfer RNA comes from the nucleolus and is synthesised within these organelles. The nucleolus may in other cases function as a transit or store or augmenter of chromosomal transfer RNA before its passage to the cytoplasm.
As a site of transfer RNA synthesis the nucleolus may be regarded as taking on an auxilliary function in protein synthesis by regulating the amount of carrier molecules supplied to the cytoplasm. In view of this numerous authors have suggested that the nucleolus is concerned principally with cell differentiation and growth, while the chromosomes are responsible for actual form by dictating through messenger RNA.
The relationship, whether direct or indirect, between nucleolus activity and cancer can now be more fully appreciated.
Much less is known regarding the synthetic site of particulate RNA. Sirlin, one of the chief present day workers on nucleoli, has pointed out that though positive evidence is small there is the possibility that the RNA incorporated with protein into ribosomal structure is manufactured in the nucleolus. Proof of this would undoubtedly strengthen the claim for an auxilliary role of the nucleolus in protein synthesis and thus in the role of growth and differentiation. Also, it has already been mentioned that amino-acids are taken up by metabolising nucleoli; perhaps both the RNA and protein fractions of ribosomes are of nucleolar origin.
Very recent experiments suggest that the nucleolus may also augment and perhaps modify messenger RNA before it passes to the cytoplasm for its coding work.
In view of what has been said above it is rather difficult to attach significance to the disappearance of the nucleolus during cell division. Some authors have suggested that nucleolar material needs a constance reshuffling or constant reseeding for metabolic activity. Others have suggested that it disappears simply because its presence interferes with chromosome movements during mitosis. Chemical and irradiation data point to a possible relationship between the nucleolus and the spindle fibres (see later). From recent observations on the formation of spindle fibre material it does not seem likely that a simple exchange of material between the nucleolus and spindle occurs. The precise relationship has yet to be found out.
This discussion could well have been headed — The changing concept of the nucleolus. Indeed, the functional concept of the nucleolus has radically changed in recent years.
The chromatin phase of the nucleus is the cell's hereditary material. Genes determine, together with the environment, both th macroscopic and microscopic features by which individuals are distinguished one from another, and also the invisible molecular structure of their various components. Chromatin is a molecular complex of nucleoprotein and it may be questioned whether or not the nature of the genetic material can be narrowed down even further. Indeed it can, for, in contrast to 20 years ago, it is now known for certain that the nucleic acid rather than the protein portion of chromatin is the genetic material.
Four macromolecules constitute the principal building blocks of chromatin (1) a simple, low molecular weight basic protein, (2) a more complex high molecular weight acidic protein (often referred to as residual protein), (3) ribose nucleic acid (RNA) and (4) deoxyribose nucleic acid (DNA). Structurally, however, two of these are of greatest importance. Experiments with differential digestion of chromatin from interphase — metabolic nuclei have shown that the morphological configuration of the chromatin, as seen under the microscope, is due to nucleoprotein complexes formed by combination of DNA and residual protein molecules. If either the DNA portion is digested (by an enzyme deoxyribonuclease) or the residual protein (by an enzyme trypsin), chromatin structure is lost completely; removal of the RNA and the basic protein molecules have no such effect.
The DNA renders the nucleus ‘Feulgen positive’. Using the Feulgen staining technique and a variety of others it has been
These findings were some of the important early pointers to the identification of DNA as the genetic material of an individual; if the characters of a species are to remain constant then so must also its determining genetic material.
In contrast, the protein portion of chromatin, both basic and residual though principally the latter, varies markedly in amount and quality from tissue to tissue and under changing metabolic and environmental conditions. Both types of protein molecules are linked to DNA as nucleoprotein complexes, and as we have seen the residual proteins impart structure to the chromatin. Functionally, however, little is known about the relationship of the protein to the genetic material though considerable evidence suggests it is concerned with the metabolism of the nucleus and cytoplasm, and perhaps also with the working of the genetic material.
Magnesium and calcium ions in small quantities are characteristic of the chromatin make up. The magnesium irons are linked to the DNA molecules at certain positions where they take the place of the protein molecules; these magnesium sites are concerned with nuclear production of energy compounds on which the functioning of the nucleus depends. There is good evidence to suggest that calcium is important for chromatin integrity.
Little is known of the RNA portion of chromatin though it is a definite structural component. The amount present is small compared with DNA and residual protein. Localised sites of RNA may be related to localised production of nucleolus material or other ‘special’ functions of the chromatin (The genetic material of some viruses [e.g. tobacco mosaic virus] is RNA, not DNA).
The chromatin of the interphase-metabolic nucleus is generally considered to be in a greatly extended and hydrated state, forming interlacing series or a network of fine fibres (Fig. 1). The electron microscope has thrown very little light on this aspect of nuclear structure. In some tissues the chromatin is readily visible after staining while in others it stains very faintly except for small scattered regions, the chromocentres. These chromocentres are generally considered to represent specialised regions of the chromatin designated as heterochromatin.
The distribution of the chromatin during the metabolic phase does not seem to be at random. Indications are that certain parts at least are located in definite sites. Observations on the distribution of sex chromatin and chromocentres have suggested that position is related to interaction between the cytoplasm and chromatin.
What seems to be a general feature of chromosomes is the presence within them of the two types of chromatin, heterochromatin and euchromatin. During a metabolic phase the heterochromatin is generally observable as darkly stained regions. The reverse is often the case in dividing cells for the heterochromatin regions of the chromosomes can only be observed with special treatments. The term ‘heteropycnosis’ is used in connection with this property of heterochromatin, i.e. it appears ‘out of phase’ with euchromatin both during mitotic divisions and metabolic phases.
Sex chromosomes (those that determine the sex of an individual), as the Y chromosomes of Drosophila, are composed entirely of heterochromatin. Otherwise heterochromatic regions on the autosome chromosomes are located adjacent to the centromeres (the chromosome's organ of movement), at the chromosome ends and at regions specialised for the formation of nucleoli.
The finding that sex chromosomes are generally heterochromatic gave rise to the early concept that heterochromatin is the basis of sex determination. The reverse seems more likely to be true, however, i.e. a change of chromatin to a heterochromatic state has accompanied the origin of sex chromosomes.
Very few genes have been located at heterochromatic regions and this and other facts have given the impression that heterochromatin is genetically inert and may be lost without severe detriment to the organism. The latter is probably true, though it now seems certain that heterochromatin is involved in the process of cell differentiation. The possible role of the nucleolus in differentiation has already been mentioned so it is interesting to note again that heterochromatic regions are often associated with regions of nucleolus formation. In maize too, certain chromosome regions (designated Ac and Ds) have been discovered which are undoubtedly concerned with genetic expression and hence affect differentiation; these regions are thought to be heterochromatic.
To account for its functional activity and staining phenomena, heterochromatin must differ from euchromatin in some general chemical structure. Nucleic acid starving experiments indicate a possible difference in DNA content but the exact nature of this or other possible differences is not understood.
Euchromatin is that part of the chromatin that is the true genetic material, concerned qualitatively with cell processes. It will be
Apart from chemical composition little is known of the ultra structure of the nucleoplasm in which the chromatin phase is distributed. Chemically it is largely protein. Structurally it is devoid of the numerous organelles and membranes present in the cytoplasm, and under the electron microscope appears as a finely granulated ground substance similar to that in which the mitochondria, microsomes, etc., of the cytoplasm are situated. A number of enzymes are present in the nucleoplasm and these are concerned with intranuclear synthesis of proteins, DNA, energy compounds, etc.
During preparations for the process of cell division the chromatin of the metabolic nucleus becomes transformed and condensed into a number of discrete units known as chromosomes (cf. Figs. 1 and 5). At the crisis of cell division, metaphase, when the actual feat of division is about to begin, these transformations are generally complete, and as the chromosomes have become arranged in an orderly manner along the cell equator (Figs. 8 and 9), this phase of division serves as a useful point at which to describe the morphology of the chromosomes.
The number and morphology of the haploid chromosome set of a species is a character, indeed sometimes a useful taxonomic character, of that species. It is known as the species karyotype. An illustration of this aspect of chromosome number is found in the New Zealand species of Hebe (Koromiko, etc.), all of which were originally referred to the northern hemisphere genus Veronica. Frankel and Hair (1937), however, looked at the chromosomes of New Zealand veronicas and found that whereas the northern hemisphere veronicas were built up of haploid chromosome sets of 7, 8 or 9, those in New Zealand were of 20 or 21. This was an important finding and was largely responsible for the New Zealand veronicas being placed in a separate genus Hebe.
An organism's haploid set or complement of chromosomes is seen in its sexually reproductive bodies (sperm, ova; pollen, embryo sac; gametes in general). The zygote formed by fertilisation of a male and female gamete will then possess two identical chromosome sets which are described as being homologous with each other. They constitute the diploid complement. When mature, the organism produces reproductive gametes by a special
Some organisms are produced from the union of gametes that possess more than one chromosome set (identical or not). They, therefore, have multiple chromosome sets in their body cells. Such organisms are called polyploids.
The haploid number of chromosomes varies greatly from species to species though closely related species often show clear relationships between their different haploid sets. The New Zealand podocarps (Matai, Miro, Totara for example) are illustrative of this point. The seven New Zealand species of the genus Podocarpus show clear morphological differences one from another. Hair and Beuzenberg (1958) have shown that clear but related differences also exist in the number and morphology of the chromosomes of the species, and that morphological and cytological differences seem to parallel each other. In his book ‘Chromosome Botany’, Darlington gives a very interesting account of the importance of chromosome studies in relation to taxonomy and evolution.
The parasitic horse roundworm n denotes the haploid number, 2n the diploid number.Ascaris, and the grassy herb Haplopappus, each have n = 2, 2n = 4Tmesipteris) have many hundreds of chromosomes and are undoubtedly polyploids. Man has 2n = 46 (Fig. 5).
Human chromosomes are about 4-6 microns in length 1 micron is 1/1000 of a mm.
Chromosome size is at least partly under genetic control (i.e. is controlled by genes within the chromosomes themselves) and is a function of a series of coils that give a ‘body’ to the chromosome similar to a spring. Under normal treatment these coils cannot be clearly seen at metaphase but on treatment with nitric acid and other chemical agents they can be made to loosen out and become quite conspicuous (Fig. 6). Each turn in the coil is a gyre, and it is the number, compactness and diameter of the gyres that chiefly determine chromosome size.
At metaphase and earlier stages of mitosis each chromosome is split lengthwise into two chromatids (Figs. 5 and 14). The chromatids are the future chromosomes of the daughter cells produced by division. Further longitudinal division of these chromatid units is still a matter of much controversy. Chromatids that have separated at anaphase are sometimes seen to be
Culex pipiens, as many as 16 sub-units have been observed, and under the electron microscope a number of workers have resolved bundles of fibril-like structures bound together in loose spirals. Each of these latter fibrils has been thought of as a nucleoprotein complex and it is tempting to consider the chromosome as a large bundle of DNA-protein complexes all arranged longitudinally and, at metaphase, the whole wound into a coil. Genetic studies, however, have shown clearly that genes are arranged as a continuous linear series of units; a number of DNA-protein fibrils each carrying its own set of genes and arranged in longitudinal parallel array could not possibly show this property. There are other equally strong objections to this hypothesis; considered cytologically and genetically a multistranded chromosome appears a quite unsatisfactory hypothesis.
We can ask then, how are the DNA units arranged in the chromosome so that the genes are aligned in the ‘observable’ linear fashion? A number of ‘chromosome models’ have been proposed in recent years in an effort to answer this question but as yet the problem is still unsettled. One possibility is that the DNA is present in a single, continuous strand. This would readily account for a linear arrangement of genes. However, measurements of the weight of DNA isolated from diverse nuclei suggest that the macromolecules are of a homogenous size, much smaller than that required to account for all the genetic material. The most recent models, then, are based on the assumption that the DNA is divided into many molecules connected in a linear series by protein material (matrix?) and arranged as a zig zag. No model yet proposed fits all the known cytological and genetical data, and the question is still open. Also, recent refined experiments indicate that perhaps the DNA molecules are larger than previously thought; that the DNA exists in a continuous strand has still not been entirely refuted.
Approached from the above angle, the electron microscope picture of the chromosome presents a new problem. Could the separate strands so seen be alignments of closely packed molecules rather than of DNA strands lying parallel to each other?
The coiled chromosome unit (chromonema as it is often referred to) is sometimes described as lying embedded in a mass of non-genetic material, the matrix. Some prominent cytologists refute the presence of this component. If a reality, its presence might account for the generally smooth outline the chromosomes present during cell division. It might function as a protective coat for the genetic material during cell division, or perhaps is related in some way to the formation or maintainance of the chromosome coils.
The centromere is the chromosome's organ of movement; chromosomes without centromeres (in aberrant individuals) do not move in strict fashion during cell division. The centromere (Figs. 7, 8 and 10) forms the primary constriction of the chromosome due to its appearance at metaphase. Especially with pretreatment with certain chemicals that markedly shorten the chromosome (e.g. colchicine), the centromere constriction is often very pronounced and the chromonema may be seen crossing the centromere (Figs. 5 and 9). In organisms whose chromosomes have been studied in sufficient detail, a number of minute Feulgen-positive granules (chromomeres or centric granules) mark the chromonema that bridges the centromeres to the two chromosome arms (Fig. 9). Whether this compound structure is of general occurrence has yet to be ascertained, but it seems justified to say that it probably is. Size is a big difficulty for the structures in
Contrary to what has long been believed, the centromere is now recognised to be double at metaphase along with the rest of the chromosome. (Fig. 7, arrow and Fig. 14). Each ‘half’ is the structural and functional centromere unit of each chromatid.
A number of animal species and the wood rushes of the genus Luzula have so called ‘diffuse’ centromeres rather than ‘localised’ ones as described above. Little is known of the structure of such diffuse centromeres but their nature of being evenly extended along the whole chromosome is attested by the fact that if the chromosome is broken into pieces, each fragment behaves normally in cell division.
So called secondary constrictions add further morphological features to certain chromosomes and seem to be generally associated with nucleolus formation. The region of nucleolus organisation is commonly marked by a very distinct secondary constriction whose presence has given rise to the rather apt terms ‘satellite’ and ‘satellite chromosome’ (Figs. 7 and 9). The satellite is double, each half again corresponding to one chromatid (Fig. 7).
The presence of a constriction at the region of nucleous organisation is probably only a feature of metaphase (coiled) chromosomes, for at earlier stages of cell division where the chromosomes are much more extended the region is not at all constricted (Fig. 3), and in maize, is marked by a very conspicuous heterochromatic swelling. McClintock has shown that in maize this swelling is the actual region of nucleolus organisation. It seems likely that the metaphase constriction is a direct result
Having discussed the double structure of centromeres, satellites and chromosomes (chromatids) it is logical to suggest that there is at metaphase, not one, but two structurally and functionally complete chromosomes. This is probably so. The two have been formed from chromosome duplication during preparations for cell division, and the two will separate and become the chromosome units of the two daughter cells after division. What continues to bind the two chromosomes together at metaphase is a problem that is not fully understood, but we shall see in the following article that the presence of two centromeres bound together, as they are at metaphase, is an important feature governing the orientation of the chromosomes along the cell equator.
This short discussion on the structure of chromosomes would be incomplete without a mention of the salivary gland chromosomes of dipterous insects, not because they add much to our knowledge of chromosome structure, but because these enormous gene houses form the principal bridge between cytology, the study of cells, and genetics, the study of inheritance. As early as 1881 Balbiani discovered the giant chromosomes in insect salivary gland cells, but it was not until some 50 years later that their importance was realised. In the following 30 years Drosophila genetics, as it is often called, has received a tremendous amount of attention, attention that has been rewarded with knowledge which surely would have otherwise remained hidden or at least obscure for a long time.
These enormous chromosomes (Fig. 11) are found in the cells of salivary glands dissected from the third instar larvae of such dipterous insects as the common fruit fly (a species of Drosophila). The chromosomes are more than 100 times as long as the equivalent metaphase chromosomes taken from, say, ganglion somatic tissue, and the largest approach ½mm in length.
Careful attention will show that each chromosome is in fact a bivalent, for longitudinal pairing, homologue with homologue, has taken place during maturation of the salivary glands, so that cells show only the haploid number of chromosomes. (Do not confuse homologues with chromatids). But more important, the chromosomes show differentiation into a series of alternating chromatic ‘bands’ and achromatic ‘interbands’. Four features of these bands will be mentioned. (1) Individual bands differ greatly among themselves and can be readily recognised and
Certain regions of the chromosomes are puffed up at various times as so called Balbiani rings. These appear to be genetic regions engaged in very active metabolism, the individual threads of the chromosomes being pushed outwards as loops. These puffs, then, are a very direct expression of gene activity.
In material which has been fixed and stained, a series of fibrous elements can be seen at metaphase extending from the so called poles of the cell and spraying outwards over the equator on which the chromosomes are aligned. Careful observations will show fibres of two sorts (Figs. 12 and 13): those extending from pole to chromosomes (chromosome fibres), and (Fig. 15), those
These four components, the continuous fibres, chromosome fibres, centrioles and astral rays (centrioles have not been identified in plant cells), constitute the mitotic apparatus. In the second part of this article we shall see how intimately these components are associated with both the division of the chromosomes into two nuclei, and the division of the cytoplasm to form two complete cells. The fibrous elements are organised as such just prior to metaphase of cell division from material preformed in the interphase-metabolic cell.
The fibre-like elements of the mitotic apparatus cannot be seen in the living cell and this fact had for many years thrown more than just a shadow of doubt on the reality of these structures; many cytologists considered until recently that the fibres were coagulation artifacts caused through fixation. It was not until 1952 when Mazia and Dan devised a unique method for isolating the intact mitotic apparatus from living sea urchin eggs, and the now famous studies a few years later by Inoue and Bajer See Mazia, in The Cell, Vol. III, 1961. The polarising microscope makes certain oriented molecules (as spindle molecules) stand out against non-oriented molecules — the phenomenon known as birefringence — and so become visible to the eye.
In three dimensional view the spindle is in the form of two cones, base to base; hence the appropriate term spindle.
The electron microscope has recently added a great deal to our knowledge of the fine structure of the spindle apparatus. In particular, the centrioles are now known to constantly consist of a series of the nine tubular fibres arranged longitudinally in the form of a hollow cylinder. The centriole is visible just outside the nuclear membrane when the cell is not undergoing division. This single structure seen under the light microscope is in fact double under the electron microscope, with two ‘sister’ cylinder-like centrioles arranged closely at right angles to each other; the sister centrioles separate as the cell enters division and take up positions to mark the poles. During cell division they reproduce themselves as double structures.
The spindle fibres themselves are also composite in structure,
Biochemical analyses and autoradiography studies have even further broadened our knowledge of these important fibrous structures. Chemically, spindle fibres have a high protein content of simple and characteristic type. RNA is also present and is thought to be built into macromolecules of nucleoproteins which together make up the spindle fibres. The spindle nowadays is considered to be a physical gel of RNA-protein molecules; the spindle fibres are regions of this gel in which the molecules are in a highly oriented state.
During their experimenting with isolation techniques, Mazia and Dan found it necessary to ‘protect’ the spindle apparatus from dissolution by the use of oxidising agents that preserve disulphide (-S-S-) bonds. Once isolated the spindle could be put into solution by reducing agents known to break disulphide bonds. This and other findings have led to the suggestion that the spindle fibres are composed principally of small protein molecules linked end to end by disulphide bonds to form an elongate, oriented protein fibre (Fig. 16).
Electron micrographs have clearly shown that the spindle chromosome fibres connect to the centromeres of the chromosomes. This is important as there is an intimate relation between the spindle fibres, the centromere, and chromosome movement. Their connection at the other end to the centriole is still not fully resolved.
Our knowledge of the structure of the spindle is bound to increase greatly in future years. Indeed it must if we are ultimately to grasp the exact mechanics of cell division. How important this is to us can be realised when it is considered that excessive uncontrolled cell division is a visible effect of cancerous and other tumerous diseases.
It will be appreciated from a mere glance at the complexity of structural organisation, from unicellular organisms such as Paramecium to man, that a great many genetic units must be carried by an organism to bring about such diversity and detail. But what exactly is a gene? Can their existence be proved or are they entirely hypothetical? Where are they? What is their chemical composition? What imparts to each its individuality? How do genes work? Today we can to some extent answer all these questions and indeed the solving of them has been one of the most dramatic achievements of present day science.
We begin with Mendel, the founder of our present day concept of inheritance. Mendel recognised and showed experimentally that the genes are carried in an organism as discrete units, are passed on from generation to generation at the same time retaining their individuality, and together express themselves in the phenotype (form) of their bearer. Mendel was unable to say what or where precisely the units of inheritance were, and it was not until a number of years later that the chromosome theory of inheritance was put forward and proved correct beyond doubt. Many experiments on the large Drosophila chromosomes and those of maize plants, among others, have shown that the genes are carried on the chromosomes, and that with the chromosomes they pass from cell to cell, and (via gametic cells), from generation to generation through the process of mitosis.
There are far too few chromosomes in an organism for these structures themselves to be the genes; the chromosome theory of inheritance recognises that the chromosomes each bear a large number of genes. The many experiments of crossing different strains of an organism (e.g., a fly with red eyes X a fly with white eyes) have made it possible to construct ‘maps’ showing the relative positions of particular genes carried by particular chromosomes of an organism (in Drosophila, maize, the bread mould Neurospora, bacteria, viruses and even in the sex chromosome of man). The chromosomes undoubtedly carry the genes.
We have noted that the chromosomes are complex chemical structures built principally of two macromolecules, protein and DNA. The question is, which of the two carry the genes, or do both of them?
To carry genetic information the molecules of a macromolecular chemical compound must have the potential of being organised into a large number of distinct combinations, each combination to correspond to a gene. Proteins are long chains of some 20 naturally occurring amino-acids, and these amino-acids can be linked together in many different combinations (to form different proteins). Proteins were for a long time considered to be the primary genetic material; different amino-acid combinations were considered to represent different genes. But starting with the experiments of Griffith using pneumonia-causing bacteria, and the ingenious experiments of a number of workers in 1952 using bacterial viruses These experiments are simply and clearly described by R. P. Levine in Genetics of the Modern Biology Series, 1962.
DNA is made up of repeated linkages of four different units called nucleotides. Each nucleotide consists of a sugar molecule (deoxyribose) with a phosphate residue attached to one side and a nitrogenous base to the other. The bases are of four kinds, two purines [adenine (A) and guanine (B)], and two pyrimidines [thymine (T) and cytosine (C)]. The nucleotides are bound together through successive phosphate bonds, and the DNA macromolecule consists of two such base — sugar — phosphate chains bound together base to base (Fig. 17). Using data obtained from X-ray diffraction studies and the results of chemical analyses, Watson and Crick in 1958 were able to propose a model for the DNA molecule. X-ray studies showed the DNA molecule to be a long, double helix. Chemical analysis showed that for each nucleotide with adenine as its base there is a corresponding one with thymine as its base, and the same with guanine and cytosine. With the knowledge that nucleotides can join together through their bases by hydrogen bonds in a very specific manner (adenine
Genetic information is contained in the order of bases within the DNA molecule. Different sequences of bases will obviously give rise to chemically distinguishable forms of DNA. Studies have shown that whereas the X-ray diffraction patterns of DNA isolated from diverse organisms all fit Watson and Crick's model, their different nucleotide ratios vary greatly from species to species. These differences correspond to differences in the gene make-up of these different organisms. It will be appreciated that many different sequences of bases are possible; it is these that form the basis of gene diversity.
We come now to a brief consideration of gene expression and the genetic code.
Genes express themselves through enzyme formation. Enzymes control cellular chemical reactions, whether or not and at what rate they proceed. Enzymes are proteins, long chains of amino acids linked together in particular array. They are very specific in their activity, for a particular enzyme will control only one or one type of chemical reaction; enzyme type, activity and specificity is almost certainly directly related to the kinds and arrangement of amino acids in its protein make-up. Cells possess a very large number of these very important compounds.
Chemical reactions determine the structure of a cell and of its components, and the cell's activities; so genes indirectly (through enzymes) control cell form and function.
Genes express themselves by dictating to the mechanism of protein synthesis the type and position of each amino-acid within its molecular structure. An indication of the currently held view of how this is brought about has been given already in dealing with RNA, and Fig. 1 in Sampson's article in a previous issue of Tuatara illustrates the essentials of the mechanism. Many details remain to be solved, but these essentials have received very much experimental support.
The genetic code concerns the problem of what sequence of nucleotides within the DNA molecule determines a particular type and position of amino-acid within a protein. Some extremely ingenious experiments have been conducted in the last two or three years in an effort to solve the problem, and while it is far from fully solved some important aspects are understood. It seems likely that three successive nucleotides dictate one amino-acid, that a particular order of bases in these triplets of nucleotides dictates a particular amino-acid, and that successive non-overlapping triplets govern the order of amino-acids in at least sections of
The codons refer to the base sequence in messenger RNA, not genetic DNA. During replication of a gene to form messenger RNA. complementation of bases occurs C to G. G to C, T to A,
In a following issue of Tuatara the mechanism of cell division will be covered in some detail. The present article has been designed as a follow-up to Sampson's article on the cytoplasm, and at this point a brief word on the relation between the two will be made: while the cell can readily be ‘dissected’ for descriptive purposes, in life no clear cut distinction between cell components exists. The organelles of the cytoplasm are developmentally, structurally and functionally related to each other. I have indicated here some interraction between the components of the nucleus, and in dealing with protein synthesis an important nuclear/-cytoplasmic interaction has been noted. As well, some exacting experiments in nuclear transplantation, particularly in Drosophila, have indicated a remarkable reciprocal interaction between the cytoplasm and nucleus. For example, when contained within the cytoplasm of a young meristematic cell, certain genes are actively expressing themselves upon the cell form while other genes are relatively inert. But transplantation of such a nucleus into the cytoplasm of a differentiated cell brings about a marked change. Those genes expressing themselves previously while in the cytoplasm of a meristematic cell cease to do so, while other previously inert genes become very active. In some way the nuclear environment, the cytoplasm, partly determines which genes are expressed, and so have some influence in the development of the cell.
The cell is a structural and functional unit.
The Sperm whale survey and marking programme which is currently being conducted by the Marine Department along the eastern seaboard of New Zealand has provided excellent opportunities to study some of the actions and reactions of this species, the largest of the Odontoceti.
Physeter macrocephalus is universal in distribution, being found in nearly all the large areas of open sea between latitudes 60 N. and 60 S. In the temperate and tropical parts of the Atlantic and Pacific Oceans it is often found in considerable numbers. Lesser concentrations are found in the Indian Ocean and the lower latitudes of the Southern Ocean. Sperm were hunted round the New Zealand coasts during the first sixty years of the last century; however the discovery of mineral oil sounded the death knell of the New England and Scots whalers who came to these waters.
In more recent years a few sperm whales which had ventured close inshore near the Tory Channel Whaling Station were taken and processed. They were not given serious consideration commercially until the collapse of the Group V humpback stock in 1962. on which the local industry had been based. The survey for sperm whales was instituted to investigate the numbers and movement of these animals to and from the Cook Strait region and adjacent areas that could be fished if the Tory Channel Company were to purchase a large steam chaser.
The sperm whale is perhaps the most interesting of the commercial whales, at least from the point of view of its distribution. The approximate geographical boundaries of the female population are between 40 N. and 40 S., but there is free movement of males outside these latitudes to colder waters. Each whaling season many thousands of sperm whales are caught south of 40 S. by the pelagic factory ships, and these are almost invariably males.
Opinions differ on the reasons for this segregation, but on the basis of the available evidence the most likely explanation would appear to be connected with the polygamous behaviour of the species. The females are normally found swimming in harem ‘pods’ or schools in the breeding grounds of the tropics, sometimes with only a single male in attendance. It is assumed that the males which move down to the Antarctic are therefore those which are unable to take control of a harem and either leave the breeding herds or are driven from them. It is known that the males fight on occasions, using their great heads as weapons to butt one another. Nor is sexual segregation of the kind found in sperm whale populations unknown; one might draw a parallel with the breeding behaviour of the Elephant Seal. Nevertheless, the ‘surplus’ bull elephants stay around the harems so the parallel is not too exact.
All observations made so far in the course of the current survey have been on male sperm whales only. The sex of adult individuals is usually easy to distinguish, since the males are about 45 feet long on average, compared with the 35 feet length of the mature female. The male usually has a prominent dorsal hump above the pelvic region. Our present data indicate that the bulk of the population moving around the New Zealand coast are mature males.
Observations on sperm whales have been made from both the sea and air. On numerous occasions it has been possible to watch individual whales for as much as an hour at a time. In February, 1963, a programme of whale marking was started, using launches of the Fisheries Protection Flotilla and locally chartered boats in selected areas. By the use of such vessels it has been possible to observe individual sperm whales from as little as twenty or thirty feet away.
Aerial observations on sperm whales have been confined more or less completely to occasions when the sea was calm and the surface wind slight or non-existent. When the surface is broken even to a small extent by spume and wave capping it becomes exceedingly difficult to pick out whale spouts from the air. In our experience it is possible to spot them from sea level in quite rough conditions, providing there is some sunlight on the water to give the spout contrast against the horizon.
Male sperm whales near the New Zealand coast have only rarely been observed travelling singly, although there is often a distance of several miles between individuals that are feeding.
Our observations on feeding behaviour in sperm whales will be discussed in the next section. In the New Zealand area the males of this species usually travel in schools or pods of about six or seven individuals. In the Antarctic, however, pods of more than a hundred have been frequently observed, though these large aggregations seem to be rarer now than in years gone by.
It is not known how long these pods stay together, since it is all but impossible to track one for any length of time. By carrying out aerial transects we have been able to determine that pods may stay together for at least several days. This was noted in November, 1962, when advantage was taken of a week-long period of settled weather. Only one attempt to relocate a pod using launches on consecutive days has been successful so far.
In most temperate and sub-polar areas the movements of sperm whales seem to be closely related to their feeding habits, though this is not necessarily so in the tropics where the breeding grounds are. In the New Zealand area we have not so far noted northward movement at any time of year. It has been assumed by other workers that the sperm whales move down to the Antarctic waters in the summer and go north again in the autumn. Our own present data suggest that in some months the numbers of male sperm whales moving south is considerably reduced, but not that in those months there is a counter drift north. Some northward movement has been observed in a few areas round the coast, but upon closer investigation this has so far been shown to be local inshore movement or movement from one bank to another for feeding.
Northward movement may take place further out from the coast than we have so far been able to observe. No hard and fast conclusions on this kind of large scale geographical movement in the New Zealand area can be drawn until much more evidence is available.
The sperm whale travels along at about three or four knots when undisturbed, but its average speed over 24 hours may be much less. Slijper (1962) gives average speeds of about ten knots and observed speeds of twenty knots. In our experience an average speed of ten knots is far too high, and the figure of twenty knots sounds improbable for anything but possibly a wounded and panic-stricken bull. It would appear that Slijper was misinformed, or that the observers had confused species. However, there is little doubt that the sperm whale is capable of sprinting to ten or twelve knots on occasion, but it is not likely to sustain this speed for more than a few minutes.
When travelling undisturbed the bull sperm whale goes through a slow, shallow and dignified porpoising movement. At the upper part of the movement the top of the head and the blowhole
The spouting rhythm of the undisturbed whale is regular, usually about once every 25-30 seconds. The beginning of the spout coincides with the front of the head breaking water, and finishes as the animal begins to sink under the surface again. The mist of the spout hangs for a second or so after the whale's head disappears.
The travelling whales are usually about a hundred yards to a quarter of a mile apart, but on several occasions two or more large males have been seen swimming along only ten or twenty feet from one another. As soon as a pod of whales reaches a suitable bank (or area of coastal shelf) and starts feeding, the pattern of movement tends to break up, and the whales move further apart.
The sperm whale is capable of very deep and sustained dives, and there are some fifteen cases on record of them found tangled in submarine cables from between 600 and 3,000 feet down. The normal food of the sperm whale is squid, which it searches out at depths of several hundred fathoms. Deep water fish such as groper and ling have been recorded in the stomachs of some of the sperm whales examined in the Cook Strait area. It is still not known whether the whale catches the squid on the bottom or in midwater. Nor is it known whether it searches actively for its food or waits passively with its mouth open.
Some whalers believe that the white mouth of the sperm may luminesce in the twilight found at 500 feet and the almost complete darkness at even lower depths, luring the squid to it. This idea cannot be dismissed out of hand, since the very fact that the sperm nearly always surfaces close to the dive point indicates possible passive feeding.
The fact of sperm whales being found tangled in submarine cables is not a sure indication that the animal is a bottom feeder, since squid are normally pelagic. It is possible that when one of the sperm whales in question became tangled, it struck the cable at a point where it hung across a narrow submarine canyon or depression.
There is a difference of opinion as to whether the whale eats its prey at the point of capture or brings it to the surface first. Although we have sometimes observed albatrosses feeding on tentacles and other squid fragments in the immediate vicinity of feeding sperm whales, it seems most probable that the sperm usually swallows its prey whole at the point of capture. The fragments that we saw may have been the result of regurgitation.
Our own observations indicate that the average feeding dive (nearly always a deep one) lasts about fifty minutes, and the whale will almost invariably bring its flukes up vertically above the surface. A whale making such a deep dive is shown in Fig. 2. Whales about to dive deeply have been observed on occasions to ‘sprint’ for perhaps a hundred yards, presumably to gain additional momentum. When the sperm whale dives without bringing its flukes completely clear of the water, it will be making a shallow dive and will almost certainly surface again well within half an hour.
Sperm whales appear to surface in a porpoise fashion from both shallow dives and normal deep feeding dives, but on two occasions we have seen sperm whales breach vertically clear of the sea. They hung clear for a fraction of a second and then fell back with a splash that was audible two miles away. This breaching probably indicates that the whale has just completed an exceptionally deep or prolonged dive. The sequence of events is shown in Fig. 3.
Sperm whales that had surfaced after dives of threequarters of an hour were seen to lie at the surface and ‘pant’, spouting at intervals often less than ten seconds; their attitude giving the appearance of almost complete exhaustion. At such times the whales are easy to approach and will not again make a deep dive until they have been on the surface undisturbed for at least ten minutes.
If male sperm whales are chased after they have just completed a deep dive, as mentioned at the end of the last section, they
When undisturbed sperm whales are approached closely by small boats their reactions are varied and interesting. Some sperm whales, particularly those appearing to be travelling steadily, will take little notice of an approaching boat, except to change course if it comes very close. This changing of course seems to be the usual reaction of sperm whales which have not been chased before. We discovered this to be true of whales approached by a boat with a slow-running engine, for example when the Fisheries Protection launches were used at half speed or slow speed.
In northern waters of New Zealand, however, we found a small pod of sperm whales which showed completely different behaviour towards the approaching boat, although we were certain that this particular pod had not been chased recently. They were moving in an area far removed from normal shipping routes, and far away from the whaling station. These whales were not observed to perform a single deep dive during the two hours that we
.
Each time a whale was approached it would repeat the sequence of sinking slowly until it was about six or ten feet under the surface. It would remain like this until it was able to manoeuvre away from the launch. It would then come up and spout again.
We were unable to mark a single whale in this pod because of this behaviour, and although four marks were fired all were listed as misses. When two of these shots were made the target whales immediately went into shallow dives accompanied by violent flurrying of the flukes as the marks struck the water beside them. Whales which had been approached and marked on other occasions showed little or no reaction as the marks embedded in their back muscle. The reactions of the first-mentioned whales seem to indicate that they are very sensitive to sharp noises in the water, and that the shock wave generated by a mark hitting the water beside them arouses more alarm than a small projectile hitting them in the back.
We also noted the reactions of sperm whales approached by fast-moving boats. In some cases the whale would dive when the boat was still about half a mile away. A similar reaction was encountered in whales approached by boats with low-revving engines when we were certain that the whales in question had been chased before. The technique used when this happened was to reach the dive point, cut the engines and wait for the whale to surface again.
Even more interesting observations were made on a number of isolated whales which had been feeding. One whale made a series of porpoising dives to avoid the launch and then sank into the water on its side, with the anterior end of the head, the tip of the left fluke and the tip of the left flipper clear of the water. From time to time as we circled the whale it lifted a considerable part of its head out of the water until the left eye could be seen.
A second whale, after being chased for some time, suddenly sank down until it hung vertically down under the water, with only the tip of its head to be seen bobbing about in the swell. Some whalers have told me that this reaction is quite commonly observed in the Antarctic, though I had not seen it before myself. These two attitudes are shown in Fig. 4.
Another bull sperm was spotted off the east coast of the South Island, moving southward and spouting normally. As we approached this whale, which was a large and solitary bull, it stopped spouting and began to move towards the boat with a considerable part of the head clear of the water.
This last whale behaved in a manner that we had not encountered in any other before. With stories of single ‘rogue’ bull sperm in mind we gave this whale a wide berth.
A brief outline of what is known of the distribution and sexual segregation of the sperm whale is given, along with a short history of the industry as it affected New Zealand.
The methods of observation used during the survey are outlined, together with a note on the weather conditions needed to spot sperm whale spouts successfully.
The group and individual movements of sperm whales are discussed.
The feeding and diving behaviour of male sperm whales are also discussed.
Some observed reactions of male sperm whales to the close approach of boats are described.
Comments on these last reactions are not offered. Considerably more data has to be collected before this kind of behaviour can be evaluated.
These are due to the Perano Whaling Company, the New Zealand Navy, the New Zealand Air Force, the Civil Aviation Authority and many individuals too numerous to name. All these have given invaluable aid in this survey.
During 1963 evidence of the catastrophic decline in the number of humpback whales passing the New Zealand coast was again noted. Only nine whales of this species were taken in the 1963 season on the northward migration, and including these nine, only fifteen seen altogether. This catch of nine can be compared with twenty-seven caught last year, eighty in 1961, and over 300 in 1960. A similar decline has been reported from Australia. Protection for the species has been agreed internationally, but it seems possible that such protection has been left so long that the species may never recover in numbers.
Similar protection has been agreed upon for the great blue whale, the largest animal on earth. This species has also declined in numbers until it is now in severe danger. The damage to these two species has been done despite the controls laid down by the International Whaling Commission. Even the stocks of the finback whale, the mainstay of the industry in the Southern Ocean, are declining year after year.
Despite the declining numbers of these three species the rarest large whale in the southern hemisphere is still the Right Whale (Eubalaena australis), which was on the verge of complete extinction when protected by the whaling convention of 1936. It was ruthlessly hunted by whaling ships and whalers based at innumerable shore stations all over the hemisphere from the beginning of the 19th century onwards. Possibly the only bright spot in the dismal picture of southern hemisphere whaling at the present time is the gradual re-appearance of this extremely rare animal in a few of its traditional haunts around the coasts of Australia and New Zealand.
The species gained its odd name simply because to the early whalers it was the ‘right’ whale to chase — easy to catch and easy to kill. Cruising along at no more than three knots or rolling
When physically mature a good male is about 48-50 feet long, and a female between 55-60 feet. In the water the whale is easily distinguished from all other species by its broad flat back, devoid of any trace of dorsal fin, a peculiar aggregation of yellowish lumps on the upper surface of the snout called the ‘bonnet’, and the fact that the spout is double, not single as in all other whales found round the New Zealand coast.
It is probably true to say that the Southern Right Whale is still the rarest large animal in the world. It is doubtful whether the number of individuals in the whole of the eastern Southern Ocean exceeds a very few hundred, even though it has been completely protected there for over twenty-five years. Prior to the opening of the 19th century the Right Whale came to New Zealand waters in very large numbers. It was extensively hunted during the period 1820-1900, and there are traces of whaling stations in a great numbers of bays and coves on both the east and west coasts of New Zealand.
The whales spent the summer months feeding in the Southern Ocean and moved north in the autumn, reaching the bays of the sub-Antarctic islands and the New Zealand mainland in July, August and September. It appears that mating must occur in shallow water in this species, although it is known that a great number of the females coming close inshore had small calves with them. From this and other evidence it seems likely that some calves were dropped in shallow water in the same months.
Not all the Right Whales in the south Pacific area went further north than the sub-Antarctic islands. A few stayed for a time
.
However, even today no more than about forty Right Whales have been seen at Campbell Island at one time, and there is no reason to assume that this does not represent a considerable percentage of the total population. At the end of the Second World War it seemed that there were fewer than ten pairs of Right Whales coming each season to Campbell Island. In the last five years it has been possible to note an as yet small, but appreciable recovery in the numbers. In the last two seasons, up to twenty whales have been seen in one bay at a time at Campbell Island, and in the winter and spring of 1963 a noticeable return has been made to the New Zealand mainland. Optimistically we hope that this means the numbers have outgrown the handful that each of the sub-Antarctic islands could support, and that the species is once again returning to the habitual movements between New Zealand and the Southern Ocean that it made a century ago in great numbers.
The Right Whales that did reach the New Zealand mainland in the early years were hunted so extensively that by 1927 fewer than a dozen individuals were being caught each year. The surviving shore stations had gone over to exploiting humpback whales long before this. By the time the species was given complete protection by the convention of 1936 it had disappeared almost entirely from New Zealand waters. Perhaps a lone whale would be reported every three or four years, but more often none at all. The bays of Campbell Island became the last precarious stronghold of the species.
The first sighting on the New Zealand mainland for many years was made, ironically enough, at the Tory Channel whaling station on July 15, 1963. The launch of the Picton harbour-master was working opposite the whaling station when one of the men on board spotted a whale coming into the channel against the tide and signalled the whaling station. One of the small humpback chasers went out to the spot. When the whale surfaced again it
At the end of August, 1963, the whaling section of the Fisheries Laboratory received a report from Bluff of a whale which came into the harbour and nosed round a fishing boat. The whale was described in such a way as left no doubt of the species. This was the second Right Whale of 1963.
On September 1 a 60ft. whale with a 15ft. calf was sighted by some fishermen near Whangarei Heads. The same whales were later reported nearer Whangarei in the channel. The mother whale was described as being ‘a little like a very large humpback with strange lumps on its head’.
Finally a 55ft. Right Whale was seen moving less than half a mile off-shore at Maraetai, near Auckland. A clear photograph of its head was obtained as it came up to breathe, and once again there was no doubt of its identity. This sighting was made on September 4, 1963.
It is unlikely that many more than these five Right Whales have been into New Zealand waters this year. The animals come so close inshore and move up the coast so close inshore that they are a most conspicuous object. The time and space distribution of these sightings makes it seem unlikely that the same whale was observed at different times at Bluff, Tory Channel, Maraetai and Whangarei. It is to be hoped, however, that there were others, and also that the species will continue to return to these waters in growing numbers each season. Mr.
The problems involved in the study of animal distribution and migration are too familiar to most biologists to warrant any explanation.
The distribution of the genus or species is largely dependent on the suitability of the habitat at a given season, either for feeding or breeding — self preservation and procreation — the two fundamental laws in Nature. I think it will be conceded that the breeding ground or grounds may be assumed to be the centre or centres of distribution — the focus from which migration proceeds. In many animals there is an interval of non-feeding during which the reserve fat (energy) accumulated at the feeding ground gradually recedes and gives place to the developing gonads. In such animals the body cavity is ‘filled’ with reserve fat at the feeding ground occupying the space freed by the receding or atrophying gonads, the reverse taking place with the approach of the breeding season. However, this generalisation does not hold good in the case of pinnipedes and cetaceans for their reserve is built up ‘outside’ the body by way of a thick layer of blubber between the muscles and the skin. No reserve is built up within the body cavity for there is little or no mesenteric fat in such animals. Nevertheless, little or no feeding is done after leaving the feeding grounds. In these animals the body cavity appears to be devoted to the development of the precocious foetus which, at birth, is frequently about one third the size of the parent.
At the breeding grounds the food is normally suited to the diet of the young. As already indicated, the adults, having laid in their store of reserve at the feeding grounds, are no longer interested in food during the breeding season. In fish, in which parental care is virtually absent, (there are some which exhibit a degree of parental care) the young of migratory species set out on their migration soon after hatching keeping up with the food supply (which itself is also migratory, or there is a change in the diet) either under their own steam or by drifting along with the ocean currents. Such migrations only cease when the cycle is closed once more on the return of the animals to the breeding grounds, when sexually mature. The migration may
The periodic migration of birds is well-known, but again the migration is largely governed by the food supply for the adults on the one hand, during the non-breeding period, and the suitable food supply and general environmental conditions for the young on the other. In many instances the quality of the food differs, not only between the young (nestlings) and the adults, but, in the chicks, it changes with advancing age. The migration may be ‘local’ or far-flung, according to species. However, I am fully aware of the numerous other factors involved in the study of bird migration which contribute to this interesting problem.
Terrestrial mammals are, perhaps, less migratory than many other forms of animal life (except Man who is invading most environments). In mountainous regions the seasonal migration is more altitudinal whereas on plains it is more dimensional. In either case it is in order to escape the weather conditions which curtail the food supply. With mammals the food of the young is secured by the provision of milk by the mother till they are able to fend for themselves; it is the food of the adult that matters.
Marine mammals, living as they do in a liquid medium, display great dimensional migration, for it is well-known that some of the cetaceans travel, periodically, through several degrees of latitude (and longitude) between their breeding and feeding grounds — breeding in warmer and feeding in colder latitudes. Again, the right food for the adult is the important factor for the young are suckled. The foetus is precocious and the young is only suckled for a comparatively short time after birth. The ample provision of stored reserve is adequate to tide the animals over the long period away from the feeding grounds. This periodical movement of cetaceans to and fro from the feeding grounds to the breeding grounds is taken advantage of by the whaling industry.
Along the course of migration, between the breeding and feeding grounds, marine animals usually leave a trail of weaklings or diseased comrades which fall out of the migratory stream, floundering at or near the surface, too weak to resist the currents and winds, and eventually strand along the nearest coasts unless devoured by scavengers. Such strandings give us a ‘line’ on the probable migratory route of the species involved. It is the similar pattern of stranding of various species of the larger animals along certain stretches of coast and not on others which I refer to as the ‘coincidental distributional pattern’.
Around New Zealand this distributional pattern is well-marked. A glance at the accompanying map will clearly indicate what is
In the course of some studies on three large pelagic fishes, the Dealfish (Trachypterus), the Oarfish (Regalecus) and the Sunfish (Mola) and among the mammals, of some of the Beaked Whales (Mesoplodon, Tasmacetus and Berardius), I was struck by the similar pattern of stranding displayed by these animals in New Zealand waters. Looking further afield, the same animals, at a generic level, followed a similar ‘global pattern’, particularly in the northern portion of the Atlantic Ocean, in the Caribbean, along the eastern shores of the United States of America and around the British Isles and the western shores of Europe. In passing it is worthy of note to observe that the New Zealand Archipelago holds a similar position in the Pacific Ocean, in the Southern Hemisphere, as does the British Archipelago in the Northern Hemisphere. However, in the New Zealand region the animals approach the area from the south following the East Australian Current, whereas, around the British Isles the animals appear to approach from the north, following the southern bend of an arm of the Gulf Stream, and strand mainly along the eastern shores. A feature common to both the areas is that the animals generally strand along the eastern shores. Stranding on the western shores is comparatively rare. However, it may be postulated that, in New Zealand, the western shores are sparsely populated and therefore fewer observations are available, but this certainly cannot be said of the British Isles! The lack of observations alone cannot account for this similarity in the two regions. The problem requires a lot more observation and knowledge of the species before any satisfactory conclusions can be reached.
Below, I give the years of stranding and locality of the various species selected for the purpose of this paper. Many others could, doubtless, be added, but this small number will suffice to illustrate the point. In addition to those mentioned, there have been other strandings for which only the date alone has been recorded, but no locality — just ‘New Zealand’. The records have been compiled from literature, museum specimens and specimens examined by myself. It is, of course, obvious that literature and museum materials have contributed the major portion of the data. In some species the period covered exceeds a hundred years. The causes of stranding are fortuitous: in some it is caused by disease or weakness; in others, accident. In mass stranding, witnessed
Globicephala) or False Killer (Pseudorca), the reasons for the mass ‘suicides’, often witnessed, are not clearly understood, but, there is the possibility that the accidental (?) stranding of one from a school may result in the stranding of the whole school, the supersonic distress calls of the ill-fated attracting the others to their doom as did the sirens of mythology !
1880, Jackson Bay; 1917, Queen Charlotte Sound; 1923, Picton; 1929, Stewart Island; 1929, Plimmerton; 1935, Nelson; 1936, Makara Coast, Wellington; 1937, Eastbourne, Wellington; 1937, Island Bay, Wellington; 1943, French Pass; 1944, Island Bay, Wellington; 1944, Plimmerton; 1950, Milton Bay, Queen Charlotte Sound; 1950, Petone Beach, Wellington; 1951, Paraparaumu; 1956, Tory Channel.
Since the last date, several other specimens have appeared in Cook Strait area. As both sexes and very young specimens have been taken in the area, there is good reason to suspect that Trachypterus breeds in the area. It is remarkable that only two specimens have been reported outside the Cook Strait area.
1860, Nelson; 1874, Jackson Bay; 1876, New Brighton Beach, Christchurch; 1877, Nelson; 1877, Cape Farewell; 1881, 1883, Moeraki, Otago; 1886, Portobello; 1889, Nelson; 1891, Banks Peninsula; 1895, New Plymouth; 1897, Waikanae; 1930, Otago; 1949, Chatham Islands.
1872, Auckland; 1872, Dunedin; 1885, Port Napier; 1889, Gisborne; 1895, Otago Harbour; 1896, Napier; 1918, Paraparaumu; 1919, Queen Charlotte Sound; 1923, Bay of Islands; 1923, Seatoun, Wellington;?, Napier; 1924, Otago; 1930, Palliser Bay; 1934, Island Bay, Wellington; 1940, Raumati Beach; 1946, Gore Bay; 1949, Palliser Bay; 1959, Rakaia River Mouth; 1951, Oyster Bay; 1951, Muritai, Wellington; 1951, Flat Point; 1952, Pakawau Beach, Nelson; 1953, Marlborough Coast; 1953, Hawke's Bay; 1953, off Kahu Rock; 1954, Blue Bay, Park Beach; 1954, Hawke's Bay; 1954, Waitara; 1954, off Waitangi, Chatham Islands; 1955, Island Bay, Wellington; 1957, Hick's Bay; 1958, Napier; 1958, Plimmerton; 1958, off Kahu Rock; 1959, Titahi Bay; 1959, Otago Harbour; 1960, Otago; 1962, Farewell Spit.
Details of the strandings of Mola in New Zealand waters are given by the author in the Records of the Dominion Museum, 4(1961): 7-20.
The New Zealand Archipelago appears to be the rendezvous for many cetaceans, particularly, some of the Ziphiidae, some of which are known to calve in the area, during the spring and early summer.
1873, Kaikoura; 1875, east coast of the North Island; 1875, Saltwater Creek; 1875, Lyall Bay, Wellington; 1911, near North Cape; 1926, Chatham Islands; 1931, Waverley Beach, Wanganui; 1935, Hawera; 1956, Palliser Coast; 1961, Kenny's Creek, Southland; dates unknown, Kaiapoi; Kawau; Great Barrier Island; Orewa; Plimmerton; Wellington; Stewart Island.
1872, Pitt Island, Chatham Islands; 1874, Saltwater Creek; 1879, Marlborough; 1901, Titahi Bay; 1912, Lyttelton Harbour; 1924, Porirua Harbour; 1937, Nukumaru Beach, Wanganui; 1943, Waikanae; 1954, Paraparaumu; 1955, Castle Point; 1960, Makara Coast, Wellington: dates unknown, Napier; Milton; Queen Charlotte Sound.
1904, New Brighton, Christchurch; 1930, Waitotara Beach, Wanganui; 1937, Manawatu Heads; 1951, Stewart Island.
The 1904 specimen was the type of M. bowdoini Andrews (= M. stejnegeri True). This species is more widely ranging than the two previous species for it occurs in both the Northern and Southern Hemispheres.
1933, Ohawe, Wanganui; 1933, Mason Bay, Stewart Island; 1950's, New Brighton Beach, Christchurch; 1962, Sumner Spit, Christchurch.
Tasmacetus is, perhaps, the rarest of cetaceans and has been recorded four times only since its first discovery. It was described by the late Dr.
1840, Otago; 1846, Akaroa; 1866, Titahi Bay; 1868, New Brighton, Christchurch; 1870, Worser Bay, Wellington; 1871, Porirua Harbour; 1873, Banks Peninsula; 1877, Wellington; 1920, coast near Wanganui; 1929, Stewart Islyand; 1931, Te Horo Beach; 1934, Otaki Beach; 1937, Plimmerton; 1944, Thames coast; 1960, Pukerua Bay.
B. arnouxi is restricted to the Southern Hemisphere. It was first described in 1846 from a specimen obtained at Akaroa.