The Crustacean Carapace

A carapace (a shield extending from the head region and enveloping a smaller or larger part of the body) is a characteristic feature of many crustaceans. This chapter reviews functional, ontogenetic, and evolutionary aspects of the crustacean carapace. Carapace morphology in Crustacea shows much variation, which is reflected in the many functions present in the various subgroups. The influential textbook by Calman 1909 on crustacean morphology and systematics suggested that a carapace was present primitively in both Malacostraca and Crustacea. This assumption was long unchallenged, but attempts have been made to invalidate/reject Calman's carapace hypothesis. Here it is argued that the best starting point may still be to assume homology, at least within Malacostraca. Whether a carapace is homologous between major crustacean taxa is more uncertain due to a general large morphological disparity.