Defensive strategies of Cladobranchia (Gastropoda, Opisthobranchia)

Abstract

Covering: up to December 2009

The focus of this review lies on the evolution of defensive systems of an opisthobranch group, the Cladobranchia. These organisms completely lost the protective shell, and employ as alternative defence strategies toxic secondary metabolites or cnidocysts. Whereas the biochemistry of several opisthobranch groups is well studied (e.g. Doridoidea, Sacoglossa, Anaspidea, and to a lesser extent Cephalaspidea), the Cladobranchia are neglected in this respect. One group within the Cladobranchia, the Aeolidoidea, is of special interest since members of this group are known to employ either incorporated cnidocysts or secondary metabolites from their cnidarian prey for their own defence. Based on the reviewed literature, we discuss the impact of sequestration or de novo synthesis of secondary metabolites, and the incorporation of cnidocysts as key features for speciation within the Cladobranchia. 145 references are cited.