Title

The role of encapsulation in the marine gastropod

Advisor Name

Jonathan Allen

Advisor Affiliation

Randolph-Macon College

Document Type

Conference Proceeding

Publication Date

1-4-2010

Abstract

Organisms that live in rocky intertidal habitats experience highly variable environments and have evolved reproductive strategies to cope with these harsh conditions. For intertidal gastropods, encapsulation of embryos is one answer to the reproductive challenge of development in both air and water. Encapsulation is often thought of as protection from predation or desiccation, but may also protect against bacterial attack, temperature shock or wave forces. Few studies have examined whether encapsulation protects embryos from predation. We conducted laboratory and field studies to test the relative levels of predation on encapsulated and unencapsulated embryos of the intertidal snail, Nucella lapillus. The offspring of N. lapillus hatch directly as juveniles, bypassing a mobile larval stage. Since N. lapillus egg capsules remain fixed to the benthos for 2-4 months, morphological protection of the egg capsule, chemical protection through reduced palatability or adult behaviors that determine laying location may all aid in juvenile survival. We designed our experiments to distinguish between the following combinations of morphological and chemical defenses: (1) egg capsules are highly protective and embryos are tasty, (2) egg capsules are highly protective and embryos are distasteful, (3) egg capsules are not protective or weakly protective and embryos are distasteful, and (4) egg capsules are not protective or weakly protective and embryos are tasty. We found high levels of predation both in the field and in the lab on all baits regardless of encapsulation or flavoring. Future directions will explore the idea that the capsules do not provide protection from predation and that adult behaviors determining capsule location may be more important to egg capsule survival.

Comments

Jill M. Dixon was an undergraduate student at Randolph-Macon College when this research was conducted.