Behaviour in Aquarium

A number of H. iris were kept in two small tanks for varying lengths of time. On February 21, 1946, four specimens ranging from 1.3cm–2.6cm were placed in each tank. One tank was aerated by sending a steady stream of air bubbles through the water for about 16 hours every day but the other was left undisturbed except for the removal and measurement of the specimens once a fortnight. The animals fed on algal growth present on the sides and floor of the tank. During the daytime the animals were invariably stationary, attached to the under side of a stone or the side of the tank near a corner although twice an animal page 6was found moving and eating in the daytime. A specimen would be in the same place during the day but would be seen moving about the tank at night. If a light were turned on immediately above them they would continue moving and feeding for ten minutes or more.

Although Haliotis is said to require very high aeration (Stephenson, 1924) the specimens in the aerated tank did not live as long as those in the non-aerated tank. Foot movements appeared to be exactly the same as those described by Lissmann (1945). Specimens often moved out of the water and when put back did not live more than a day. A possible explanation of this behaviour was that there was a change in the salinity of the water.