What's in a Name?

Since the days of Lineaus, scientists have attempted to group all living things into a hierarchy, according to their familial relationships, not unlike the genealogies we use in our own family trees. In such a hierarchy, animals are divided into two groups: Invertebrata refers to animals lacking a vertebral column and Vertebrata to those possessing a backbone. Lobsters share the largest of the invertebrate phylum, the Arthropoda (from the Greek, arthron, meaning joint and pous meaning foot), with the insects, spiders, and various other creatures having an exoskeleton (outer skeleton) instead of a backbone and bearing jointed appendages. The phyla, making up the classification hierarchies, are further subdivided into classes, orders, families, genuses, and species. The lobsters, along with their cousins the crabs, shrimps, and copepods, are included in the class Crustacea because they bear a flexible shell (from the Latin, crusta), which distinguishes them from those animals bearing hard and brittle shells, such as oysters, mussels, and clams. Lobsters are then placed in the subclass Malacostraca, again to stress the fact that their shell is soft compared to the harder-shelled molluscs. Because lobsters bear ten legs, they are placed in the order Decapoda (from the Latin, meaning ten feet).

The different kinds of organisms we call lobsters are further subdivided into the suborder Macrura Reptantia (from the Greek, makros meaning long, oura meaning tail, and the Latin, reptans meaning crawling habit - - or a long-tailed, crawling animal) which consists of three infraorders: the Astacidea (marine lobsters and freshwater crayfishes), Palinuridea (spiny and slipper lobsters), and Thalassinidea (mud lobsters). The infraorder Astacidea contains three superfamilies: the Nephropoidea (the commercially important marine lobsters) and the Astacoidea and Parastacoidea (freshwater crayfishes of the northern and southern hemispheres, respectively). Similarly, the infraorder Palinuridea contains three superfamilies: the Eryonoidea (deepwater species), the Glypheoidea (a fossil group with only one living representative), and the Palinuroidea (the commercially important spiny and slipper lobsters). The infraorder Thalassinidea consists of only one superfamily, the Thalassinoidea, which are used as both food and bait.

Lobsters and crayfishes of the infraorder Astacidea are distinguishable from other lobsters because they bear pincers (or chelae) on the first three pairs of legs. The first pair of legs is always the largest. Of the Astacidea, we will only consider the true lobsters or those belonging to the superfamily Nephropoidea. There are two families within the Nephropoidea - - the Thaumastochelidae and Nephropidae - - it is the latter that contains the lobsters belonging to the genus Homarus which are covered here.

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