For anyone with interests in a group of organisms as large and diverse as the Crustacea, it is difficult to grasp the enormity of the entire taxon at one time. Those who work on crustaceans usually specialize in only one small corner of the field. Even though I am sometimes considered a specialist on crabs, the truth is I can profess some special knowledge about only a relatively few species in one or two families, with forays into other groups of crabs and other crustaceans. Crabs are but a small picture of the overall diversity of the Crustacea. They represent only one infraorder [Brachyura] within one order [Decapoda] within one superorder [Eucarida] within one subclass [Eumalacostraca] within one class [Malacostraca] of the six currently recognized classes of the Crustacea (as depicted herein). I am certain that this situation is similar for all other crustacean systematists, with the result that there are no living specialists who can truly claim to have an in-depth understanding of the Crustacea as a whole....

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