The Settling and Some Experimental Reactions of a Bryozoan Larva, Watersipora cucullata (Busk)

Abstract

The external anatomy and behaviour of the pelagic, crawling, and settling stages of Watersipora cucullata (Busk) are described. The main settling period in Sydney Harbour appears to be February-April. The usual negatively phototropic reaction at settling in subdued light could be reversed by increasing the illumination. There was some evidence of gregariousness. When "non-filmed" settling surfaces were offered settling was delayed and a high mortality appeared. In copper solutions of 2.5-5.0 mg Cu/l. larvae settled considerably faster than the controls but metamorphosis was abnormal and lethal. No such acceleration of the settling rate was observed in mercury solutions of the same strength but these appeared to be relatively more lethal.