Tuatara: Volume 20, Issue 2, March 1973
Some Ethological and Biological Observations on the Tuatara in Laboratory Conditions
Some Ethological and Biological Observations on the Tuatara in Laboratory Conditions
The arrival of a live male specimen of tuatara (Sphenodon punctatus punctatus (Gray) at our Department early in August, 1963 provided an opportunity for the study of the following aspects of that animal. Firstly, there was the problem of the animal's reaction to the sudden reversal of its daily and seasonal rhythmicity following a flight from New Zealand to Poland of some 40-50 hours. Secondly, as the existing information on the tuatara's biology is still relatively scarce, an attempt was made to collect more data. Finally, we were interested in the susceptibility of the tuatara's senses and particularly to find out whether the animal's parietal eye would react to thermal rays.
Maintenance of the Animal
Our specimen was an adult male of the typical form of S.p. punctatus (Gray) conforming to the descriptions by Wermuth and Mertens (1961) and Dawbin (1962). It was kept in a large metal vivarium of 110 × 70 × 70cm, specially constructed, provided with glass panes on two sides, netting on the remaining sides and a 25cm high ridgeroof. During the first months, the vivarium's bottom was covered with a 15cm deep layer of soil to allow the animal to burrow underground gangways and holes. At a later stage when the tuatara became infected with a kind of scurvy, the soil was removed, the vivarium was disinfected, a wooden shelter was added and the animal remained in this accommodation until the end of its life.
Results of Observations
1. Food and Water
Initially our tuatara was fed with earthworms, which it took readily like Merten's (1958) specimen, but once a start was made feeding it with larvae of meal worms (Tenebrio molitor), it much preferred these to earthworms. At a later date, our tuatara, like that of Werner (1926) also took young, still naked mice. An attempt was made to feed the tuatara with snails but it refused to eat them and even drew away their mucous bodies with obvious dislike each time a snail managed to creep on to it.
Our tuatara maintained a reasonably good appetite while it remained in good health. For instance, in August, 1963 it consumed a record daily amount of food consisting of 17 earthworms and 29 page 98 mealworms, both larvae and fullgrown, and at that time consumed daily an average of 8 earthworms and 18 mealworms. In September the tua tara consumed in one day 8 earthworms and 18 mealworms and its daily average was 4-5 earthworms and 23 mealworms. At a later stage, when it became sick, its appetite was reduced and there were days when it refused to take food.
The tuatara regularly took some water but the amount consumed could not be recorded. In natural conditions the tuatara has been reported to consume water but mainly after eating marine foods. Our specimen liked bathing in a tank provided for this purpose in the vivarium. It also swam well though it disliked diving.
2. Hollow Dens
In natural conditions the tuatara dwells in burrows which it digs out in soil, sand or clay. In the vivarium the tuatara dug out initially one gangway some 60-70cm long running horizontally though somewhat obliquely in which it could hide itself. Its usual position was to have only its head sticking out of the burrow's entrance. At a later stage, our specimen dug out another gangway which it used in the same way as the first. When digging the animal used each foreleg alternately, throwing soil to the back. Upon leaving the burrow it was covered with dirt, but this was soon washed off by bathing in the tank. One of the gangways had a second opening and could be used by the animal as a tunnel.
The tuatara defends the entry to its burrow against any intruder. A hand levelled at the burrow's entrance was immediately attacked by the tuatara's strong teeth. Mertens (1958) recorded in his male tuatara such aggressive behaviour that he could not get close to it. Our specimen, though also a male, behaved differently: from its arrival it was quite tame and did not attack anything and sometimes would even accept food presented on forceps by its keeper. Exceptional behaviour was noted when the animal was being caught: it assumed a warning position by lifting itself on its forelegs and opening its mouth widely to show its teeth and also its strong, thick tongue. This threatening behaviour was followed by an attack with a sudden, sidewise twist of the head allowing the hand to be caught from one side. In addition to this type of defence, the tuatara can hit its adversary strongly with its snout to the extent of causing bruises. An excited tuatara, particularly when being caught utters sounds that can be described as short, strong croaks.
Despite an association with marine birds living in the same burrow, the tuatara has an essentially solitary way of life, and except during the mating season one does not find two animals together. Males are known to be unfriendly towards other males page 99 and bloody fights have been reported. With this inclination towards a solitary way of life, the tuatara's curiosity towards man is puzzling. Sladden and Falla (1928) observed tuataras in natural conditions —emerging from their burrows to watch people camping nearby. Our tuatara lived in a room in which seminars involving staff and graduates were held between 18.00 and 20.00 hours. During these meetings, one could often observe the tuatara leaving its burrow for the highest place in the vivarium or the top of a branch set inside and looking at the people seated round. One could also note that any person speaking attracted the particular attention of the animal. Once this person stopped talking and another person began speaking, the tuatara would turn its head in the latter's direction. This would perhaps confirm the views of other research workers who claim that the tuatara has a well developed sense of hearing which may be particularly useful in hunting for insects rustling in grass.
The tuatara utters two different sounds: one emitted in excitement is not unlike a loud short croak; and the second sound is much weaker and reminds us of a growl or groan. A bioacoustic analysis of the first sound has been given elsewhere (Wojtusiak and Majlert in press) but there was no opportunity for recording the second sound, nor for its analysis. It is possible that the second kind of sound may be of some importance during mating displays or during feeding but no proof has been found so far for this.
A. Sight: Our observations show that the sight of the tuatara is well developed. The presence of food could be recognised from a distance of 50-60cm and this would confirm previous observations (Werner, 1912 and 1925). However, in catching a prey it seemed to be more directed by movement than the perception of shape. It has been reported to have better sight at night and this prompted us to experiment with the sensitivity of this reptile to infra-red radiation.
B. Sensitivity to Infra-red Radiation. The tuatara has a well developed pineal gland or parietal eve, the structure of which reminds us of a third eye (Dendy 1910 and 1911, Stebbins and Eakin 1958, Stebbins 1944, Cans and Parsons 1970). It is well developed in young specimens and not covered by scales (Anonymous 1954) which grow upon it at the age of six months. The presence of a retina and lens (Gabe and Saint Girons 1961) in the parietal eye located beneath the skin but not covered by one, make it conceivable that it could function as an eye sensitive to infra-red radiation and be of assistance to the animal in orientating itself during the night. According to Anthony (1970) it was Ruckard (1886) and Francotte page 100 (1887) who attributed to the pineal gland a thermoregulating function, though this has not yet been tested experimentally. According to Novikoff (1910) and Dendy (1911) the parietal eye may record differences in the intensity of visible light. A sleeping tuatara would be able with the help of its third eye to perceive changes in light intensity caused by screening the sun by a shield or by an approaching body. However, research work by Stebbins (1958) did not answer positively the question of the sensitivity of the tuatara's parietal eye. In order to ascertain the tuatara's sensitivity to infra-red radiation some preliminary experiments were carried out with the help of a small infra-red telescope. This instrument consists of a lamp emitting infra-red radiation, a receptor telescope and a feeder of high intensity current of about 22.000 volts. The telescope allows one to see the radiation reflected from the given object owing to a screen which when stimulated by infra-red radiation produces a visible light. The tuatara illuminated by infra-red radiation did not show any reaction, although one could see the animal well through the telescope on the specific willow green lighted screen despite complete, external darkness. Despite directing the telescope from various angles on the tuatara, no reaction of the animal, such as directing its head towards the lamp emitting infra-red radiation or otherwise was noted. Admittedly, our experiment may have been of a too short duration for the animal to become aware of the infra-red radiation. Similarly Dendy (1910) working in a similar way was also unsuccessful in obtaining any reaction of the animal to visible light. We may conclude that despite the use of our method of direct observation in infra-red light the problem of the sensitivity of the tuatara's parietal eye remains unsolved. In future, the problem should be investigated by training the animal with segments of light containing infra-red radiation. If the animal could distinguish these light segments from other segments with a similar radiation but deprived of infra-red rays as has been done with aquatic turtles (Wojtusiak 1949, Wojtusiak and Mtynarski 1949), the seeing capacity of the parietal eye could be proved. Electro-physiological experiments would also assist in the solution of this problem. Unfortunately, the illness of the animal discussed below, prevented the carrying out of any further experiments.
C. Other Senses. It would appear that the tuatara's taste is also well developed. The preference for mealworms over earthworms, which the animal refused to eat, would support this statement. This is in accordance with observations of other authors (Werner 1913 and 1923 and Wettstein 1931) who reported cherries taken being distastefully spitted out, as were snails in the case of our animal. This is interesting because in its home, the tuatara has been reported to consume snails of the species Janella schaumslandi Plate, but European snails were obviously disliked.page 101
|Number of observations|
|Number of observations||Hours||6-13||13-22||6-13||13-22||6-13||13-22||6-13||13-22||6-13||13-22||6-13||13-22||6-13||13-22||6-13||13-22|
|% of activity||67.7||61.5||59.0||48.4||43.6||34.0||37.0||46.6||40.0||59.3||33.3||62.0||56.0||66.7||37.5||83.3|
7. Daily (Twenty-four hours) Activity
The tuatara is a nocturnal animal and this is indicated by its pupils which narrow during the day into a vertical slit. In subdued light the pupil is round which, together with the relatively large size of its eyes gives the tuatara a more “human” expression than other reptiles. Merten's (1958) male specimen was timid, hiding either in a burrow or in a shelter made out of boards which it left only at dusk. It took that specimen several months before it would emerge in the daytime and it never came out in sunlight or even during a bright day. Our tuatara did not avoid people, did not hide nor avoid diffused light or sunlight. It was active during the day taking food, climbing up the branch set in the vivarium, bathing in the tank and resting on the ground of the vivarium.
It should be borne in mind that our tuatara had been shifted from the full winter in the Southern Hemisphere to mid-summer in the Northern one. As there is between New Zealand and Poland a time difference of about 11-12 hours, our tuatara, which in its home country was active at night, had fairly suddenly found itself at the same time of the day in conditions of full daylight.
The behaviour of our tuatara described above seems to indicate that the animal during the first weeks or even months of its stay in Poland adhered to its former activity period which involved a change from nighttime activity in New Zealand to daytime activity in Poland. The fact that the tuatara did not avoid sunshine or light would indicate that its nocturnal activity is not entirely dependent on the day and night rhythm. Several months later our tuatara would usually leave its burrow in the morning, about noon and in the evening. A particularly high nocturnal activity occurred during the heatwave during the summer. This was shown by the soiling of the vivarium's walls: foot marks could even be seen on the hip of the vivarium's roof which would indicate a climb of 60-70cm above the terrarium's surface.
Observations carried out by Madame J. Gieszczykiewicz during the first four months of the tuatara's stay in our laboratory provide some information on the gradual change in its activities.
During this time the animal had been kept at a constant temperature of about 20 C and meteorological observations were recorded on a thermo-hydrograph and a barograph. Lack of space prevents us from including diagrams from which we can conclude that changes in atmospheric pressure and humidity had little or no effect on the daily activities of the animal.
The activity of the tuatara has been divided into the following five categories:page 103
1 Rest or inactivity
2 Walking or bathing
3 Eating and drinking
5 Climbing and attempts to escape.
It would have been of considerable interest to find out how the tuatara's activity gradually shifted into the night, unfortunately no appliance for an automatic registration of its activity during the night was available.
8. Annual Activity
In concluding, it would appear that the rapid adaption of our tuatara to its new environment was facilitated by the summer conditions and particularly by the high temperatures that it encountered on its arrival in Poland.
9. Adaptation to Temperature
The tuatara differs from other reptiles in its adaptation to relatively low temperatures (Batham 1960). Its optimum ambient temperature is between 12 and 13°C which according to Bogert (1949) and Mertens 1958) conditions its longevity. Our specimen came from Stephens Island, where April temperatures are reported to be between 9.4 and 14.0°C with a mean of 12.2°C, but in November, when tuataras are most active, temperatures from 8.8 to 13.7°C, with a mean of 11.4°C occur. The tuatara's body temperatures recorded in November (Dawbin 1949 and Bogert 1953 a and b) were 7.6° to 13.3°C with a mean of 10.6°C.
Our own observations seem in indicate that at temperatures below 16°C a decline in the tuatara's activity was noticeable. Temperatures page 107 between 16 and 18°C (which was the temperature of the room where the tuatara was kept) seemed to be the most favourable and the animal showed the greatest activity, a sound appetite and was in a fine fettle. At 20°C the tuatara was still active but above 24°C there was a decline of its activity, appetite and general well-being. At still higher temperatures, the tuatara would often open its mouth, lie supine with extended legs, looking as if it were dead. It was obvious that the tuatara would, at such high temperatures that prevailed at this time in Poland, survive only a short time and its quarters had to be airconditioned to bring the ambient temperatures to 16-18: and exceptionally to 20°C.
10. Illness and Death
The tuatara lived in our laboratory for nearly three and a half years and died on February 9, 1967, as the result of disease. Upon the animal's arrival the presence of several, large grey-green, 5mm wide ticks, well adapted in colour to the skin of the host, were noted and removed. (Apedonoma sphenodoni). The scurvy of the mouth proved to be a serious ailment. From the pus the following bacteria were identified: the pathogenic Staphylococcus pyogenes, var. aureus and two saprophytic bacteria Micrococcus sp. and Sarcina lutea. An antigramme of S. pyogenes has shown an average sensitivity to standard antibiotics.
Our tuatara was attended by veterinary surgeons, trained in pathological aspects of zoological gardens. Fig. 4 shows the regeneration after the operation on the upper jaw. During its convalescence, the tuatara resumed feeding and soon recovered a healthy appearance. However, later it became ill with scurvy again and this time the scurvy attacked the inner organs and caused its death. It would be of some interest to find out whether similar cases of scurvy occur not only in captivity but on Stephens Island and other islands with tuataras in New Zealand.
The specimen and its skeleton have been presented to and are deposited in the Zoological Museum, the Jagellonian University in Cracow.
Our specimen of tuatara was presented by the Government of New Zealand to the Jagellonian University in Cracow on the occasion of the 600th anniversary of its foundation. I would also like to thank Professor Zygmunt Grodzinski, Director, K. Hoyer's Institute of Comparative Anatomy, Jagellonian University for kindly handing the specimen to our Laboratory and for reading early drafts of this text.
Our thanks are due to Mr D. M. Luke, New Zealand Department of Internal Affairs for all the arrangements connected with the catching of the specimen and its transport from Stephens Island page 108 to Cracow. I am particularly indebted to Madame Janine Gieszczy-kiewicz for the upkeep of the animal and for carrying out some observations. Doctors A. Taborski and S. Zapletal, of the Zoological Gardens in Pozman and Cracow respectively and Dr H. Franckiewicz attended the tuatara during its illness and Professor J. Starzyk, Cracow Medical School analysed the bacterial strains.
Last but not least I would like to thank my friend and colleague Professor K. Wodzicki, F.R.S.N.Z., for his initiative in the procurement of the specimen and for the translation of the text into English.
Anonym. (Dawbin W. H.) 1954: First home-grown Tuataras, Natural History (New York) 63: 422-423.
Anthony J. 1970: Le Névraxe des Reptiles, in: P. P. Grassé: Traité de Zoologie, Vol. 14, fasc. 2: 680 XXXII pp. Paris, Masson et Cie.
Batham E. I. 1960: Report on female tuatara at Portobello Aquarium. (Manuscript obtained from the Internal Affairs of the New Zealand I. A. 46-18-36, August 18, 1960).
Bogert, C. M. 1949: Thermoregulation in reptiles, a factor in evolution. Evolution 3: 195-211.
——, 1953: Body temperatures of the Tuatara under natural conditions. Zoologica, New York 38: 63-64.
——, 1953: The Tuatara: Why is it a lone survivor? The Scientific Monthly 76, (3), 163-170.
Dawbin, W. H. 1949: The tuatara. Tuatara 2: (2) 91-96.
——, 1962. The tuatara in its natural habitat. Endeavour 21, (81): 16-24.
Dendy, A. 1898: The life-history of the Tuatara (Sphenodon punctatus) Trans. N.Z. Inst. 31: 249-255.
——, 1911: On the structure, development and morphological interpretation of the pineal organs and adjacent parts of the brain of the tuatara (Spenodon punctatus) Trans. Roy.Soc.London 201 B: 227-331.
——, 1910: On the structure, development and morphological interpretation of the pineal organs and adjacant parts of the brain in the Tuatara (Sphenodon punctatus) Anat.An. 3 37: 453-462.
Dendy, S. 1899: Outlines of the development of the Tuatara, Sphenodan punctatus. Quart.J.Micr.Sci. 42: 1-87.
Gabe M. and H. Saint Girons — 1964: Histologie de Sphenodon punctatus. Editions du Centre National de la Recherche Scientifique, Paris: IX-148
Gans C. and T. S. Parsons, 1970: Biology of the Reptilia. Vol. 2. Morphology, B. Acad.Press London, New York: XIV — 374.
Mertens R. 1958: Eine lebende Tuatara oder Brückenechse. Natur und Volk 88 (1) 15-21.
Nowikoff M. 1910: Untersuchungen über den Bau, die Entwicklung und die Bedeutung des Parietalauges von Sauriern. Z.wiss.Zool. 96: 118.
Sladden B. and R. A. Falla 1928: Alderman Islands. A General Description, with notes on the Flora and Fauna. N.Z.J. Sci. and Techn. 9: 193-205 and 282-290.page 109
Stebbins R. C. 1944: Some aspects of the ecology of the iguanid genus Uma. Ecol.Monogr, 14: 331-332.
——, 1958: An experimental Study of the “Third Eye” of the Tuatara. Copeia No. 3: 183-219.
——, and R. M. Eakin 1958: The role of the Third Eye in reptilian behaviour. Am.Mus.Novitates 1870.I: 40.
Wermuth H. and R. Mertens 1961: Schildkröten. Krokodile. Brückenechsen. G. Fisher, Jena: XXVI — 422.
Werner F. 1912, 1925: Brückenchsen. Rhynchocephalia in: Brehms Tierleben, Vol, 4. Lurche u.Kiechtiere. IV. Aufl. IV. Neudruck, Leipzig: 358-373.
Wettstein O. v. 1931: Rhynchocephalia. Kückenthal-Krumbach: Hdb. d.Zoologie. 7: pt.1: 1-235.
Wojtusiak R. J. 1948: Investigations on the vision of infra-red in animals, I. Investigations on water tortoises. Bull. Acad.Polon. Sc. BII Cracovie: 43-61.
——, and Z. Majlert in press: Bioacoustics of the voice of the Tuatara, Sphenodon punctatus punctatus Gray.
——, and M. Mynarski 1949: Investigations on the vision of infra-red in animals. II. Further experiments on water tortoises. Bull.Acad.Polon.Sc., B.II Cracovie: 95-120.