A CONTRIBUTION TO THE BIOLOGY OF A DEEP SEA ECHINOID, ALLOCENTROTUS FRAGILIS (JACKSON)

Abstract

A study of the reproductive cycle of Allocentrotus fragilis, was made in Monterey Bay, California, on material collected on a monthly basis from depths of 68 to 100 fathoms. Mature gametes were obtained in Feb. - March, 1957, and during Sept., 1957 - Jan., 1958. Spawn-out occurred between Feb. -March during both years. The nature of the habitat was found to be relatively flat - gravel and sand; underlaid with gray silt, containing organic detritus and microscopic organisms. Gut content analyses of A. fragilis revealed small animal and organic debris as in the bottom sediment. Attempts to correlate the life cycle of A. fragilis with the environmental factors led to the suggestion that upwelling may trigger spawning, so planktonic larvae presumably develop during the time when the planktonic bloom occurs.