The effect of age on the adult-produced larval settlement cue in Dendraster excentricus

Abstract

A settlement cue produced by adult Pacific sand dollars, Dendraster excentricus, maintains dense aggregations of the species by inducing the metamorphosis of their larvae. This process is well-studied, but the unknown details are many. In May 2019, while studying at Friday Harbor Laboratories on San Juan Island, I attempted to add to the knowledge of this process by hand-rearing larvae and introducing them to sand which had been conditioned by adults of different sizes. The settlement data collected, while limited and nonsignificant, suggests that the 12-day timeline was sufficient for the adults to condition the surrounding sand, and that it is produced by adults, both big and small. Any nuance in the response to the cue remains to be discovered and could shed light on the adaptations to communal living in Echinoderms.