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8 CLASSIFICATION AND TAXONOMY OF CRAYFISH When I was in biology classes in school we learned that all organisms were ranked taxonomically. The ranks were: Kingdom, Phylum, Class, Order, Family, Genus, Species. It was a way to show how everything was related to everything else. These ranks were drummed into our feeble minds to the point that I can cite them in my sleep. But it has now gotten more complicated what with superfamilies and superorders and a mixing up of the interrelationships. So, where do the crayfish fit? First off, they are in the Kingdom Animalia. Within the Animalia are the Arthropoda or 'joint-footed' animals. All arthropods have several things in common which include; the body is bilaterally symmetrical, has an exoskeleton, possesses pairs of jointed legs and is divided into two or three sections. Most have a straight-through gut, a nervous system with a brain and ganglia, and an open circulatory system. Within the Arthropoda are the Crustacea which have a body with three parts. Within the Crustacea are Malacostraca ('soft-shelled') and within that are the Decapoda ('ten-footed') which include crabs, lobsters, crayfish and shrimp. Within the Decapoda are the Astacoidea which are the crayfishes. These are split into the Astacidae and Cambaridae. The Astacidae are native to Europe and western North America. Our crayfishes are in the Cambaridae which is the largest group with over 390 species in eastern North America and Asia. There are 12 genera within the Cambaridae of which only three [Procambarus, Cambarus and Orconectes] are found in Nebraska. These three can be most easily separated by looking at the first pleopod of a male. In Procambarus, the pleopod ends in three or more short extensions. These are often hidden by setae. There are some 160 species in Procambarus of which Nebraska has one native and one (so far) non-native species. In Cambarus, the tip of the pleopod has two short, thick and laterally flattened elements that are sharply curved. There are about 100 species of Cambarus of which one is found in Nebraska. Orconectes has a pleopod with two thin extensions that may be long or short and curved or straight. There are some 85 species of Orconectes of which three native and one non-native species are found in Nebraska. One thing you will soon learn is that most crayfishes have no common names. This is evident in the variety of regional names for crayfish. Names such as crayfish, crawfish, crawdad, crawcrab, crab, stonecrab, creekcrab, mudbug and, in French, ecrevisse. So where did the name "crayfish" come from? The online Free Dictionary (http://thefreedictionary.com/Astacoidea) says it probably came from Old German, krebiz ('edible crustacean') which became the French crevise or ecrevisse. The crevise then morphed into the English crayfish. These are terms for crayfish in general, not for individual species. Why? Well, "common" names, as opposed to the Latin binomial or the "scientific" name, is a name that is in "common" use. It is a name Orconectes Procambarus Cambarus