Ontogeny of shell-related behaviors and transition to land in the terrestrial hermit crab Coenobita compressus H. Milne Edwards

Abstract

The marine megalopa of the terrestrial hermit crab Coenobita compressus wears a small gastropod shell that it carries onto land before metamorphosing into a juvenile crab. This paper gives the first detailed account of temporal shifts in shell-related behaviors that occur as the megalopa approaches metamorphosis. Megalopae placed in individual containers shortly after metamorphosing from the last zoeal stage exhibited three behaviors: shell inspection, followed by shell wearing in water, and finally by shell wearing on land. Megalopae experimentally denied access to shells exited the water at about the same time as megalopae with shells, but they wandered about on land for shorter periods of time before burying themselves in sand and attempting to metamorphose. Once buried, megalopae without shells often emerged and re-buried themselves at other locations in their containers; almost all shell-less megalopae died without metamorphosing to the first juvenile crab stage. Once buried, megalopae with shells rarely emerged without first metamorphosing to the juvenile crab stage, and they metamorphosed significantly more frequently than those denied shells.