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Behaviour

H. iris is a nocturnal animal. During the day it is always found away from direct light attached underneath ledges or on boulders. The small specimens are usually found on boulders or stones while the larger specimens in deeper water are generally attached to rock walls or overhanging ledges of rock. At no time during the day was a specimen seen moving unless it had been disturbed. When disturbed they cling tenaciously to the surface of the rock. Occasionally an animal would move from the exposed surface of a boulder that had been disturbed to the lower surface. This movement away from the light, however, occurred fairly frequently in the case of disturbed H. australis. Some specimens were attached to a broken piece of concrete and one had attached itself to a strip of rusty tin. This seems to point to the fact that they will attach to almost anything as long as it gives firm support and is out of direct light. It seems probable that where such a large number of specimens occurs in a small pool as described previously they must move out of such a pool during the night to feed, as often there is little or no algal growth on the rocks to which they are attached.

In one pool the writer observed a Haliotis (approximately 10cm in length) which on successive visits over a period of 3 months was still situated in the same place on the same rock. In addition, on 3 occasions on the removal of an animal from a rock there was left a definite mark on the rock where the animal had been attached. In one case a large surface of the rock was covered by small white tube worms except where a Haliotis had been removed and there remained a smooth surface of rock in the exact shape of the shell. From the above facts it is highly probable that H. iris has a homing instinct in its nocturnal movements. This view is supported by observations of the aquarium specimens. Graham (1941) expresses the opinion that Haliotis undergoes a winter migration to deeper water at Seal Point, Otago. This is a popularly held opinion. On the other hand a commercial fisherman in Island Bay, Wellington, who fishes for Haliotis throughout the year maintains that they do not migrate in the winter but can always be obtained at the same levels.

H. australis when found in any numbers was always intermingled with H. iris and never seen in groups of more than 2 or 3 as is often the case wim H. iris. It was more active than H. iris if disturbed and invariably quickly found its way back to the pool if placed out of the water on a nearby rock. On one occasion 4 small H. iris about 2.3cm in length were placed with a H. australis of the same size in an upturned billy lid. In about half an hour the H. australis had crept over the edge of the lid at least 3 times while all the H. iris remained completely immobile. H. iris specimens show a tendency to leave a pool if disturbed. In three cases specimens were noticed in the same positions on successive visits over a varying period ranging from a few weeks to about 3 months but in every case when lifted for measuring and disturbed they disappeared very quickly from that pool. H. iris if turned on to its back will right itself in the same manner as described by Crofts (1929).