Materials and Methods

On 1.7.70 15 adult T. robustum were placed in an asbestos aquarium (2.5 × 0.38 × 0.23m) at the Island Bay Marine Laboratory. Several stones and Haliotis (paua) shells were placed in the aquarium to provide shelter and objects on which to spawn. The tank was supplied with fresh running seawater and the fish were fed chopped liver and fish. On 8.7.70 freshly laid eggs were found on the undersurface of one of the Haliotis shells. These were attended by a male T. robustum (78mm s.l.) which, along with the eggs, was removed from the asbestos tank and placed in a small plastic aquarium (30 × 28 × 13cm). The water was changed daily and kept constantly aerated.

On 25.7.70 a similar system was set up using 10 adult T. capito, but no spawning occurred. However on 28.8.70 an egg mass on a portion of clay pipe was collected from the Island Bay shore and kept in a plastic aquarium (30 × 28 × 13cm), along with the adult male T. capito found attending the eggs. The water was changed and aerated in the same manner as for T. robustum.

Eggs of both species required for observation were easily removed from the substrate by sliding a scalpel or mounted needle beneath the egg and then pipetting the dislodged egg into a petri dish.

Development of these eggs was studied and sketches of the eggs and larvae were made using a camera lucida. An ocular micrometer was used for measuring eggs and larvae. Measurements of the larvae were based on those recommended by Hubbs and Lagler (1958), with the exception of head length, taken here as the distance from the tip of the snout to the back of the otic capsule. This is more definite than the opercular flap which is often not readily visible. Egg and larval terminology is based on that used by Rugh (1948), Balinsky (1965) and New (1966).