Experimental Selection of Attachment Substrate by an Abalone Nordotis discus (REEVE)

Abstract

Selection of attachment substrate during daytime by the abalone Nordotis discus was studied in an experimental box over two seasons, summer and winter. Animals preferred narrower spaces between near horizontal surfaces and attachment upside down on the upper surface. Respiratory holes were not preferentially turned towards an open area. Abalones attached by raising their right or left side more frequently than by raising the head or posterior. The number of abalones raising the right side was almost equal to that raising the left side. Individuals aggregated in summer better than in winter. The larger abalones were in size, the more they attached with a supine posture and 89% of total number of adults tested adopted this posture.