The name "crayfish" comes from the Old French word escrevisse (Modern French écrevisse). The word has been modified to "crayfish" by association with "fish" (folk etymology). The largely Americanvariant "crawfish" is similarly

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The body of a decapod crustacean, such as a crab, lobster, or prawn (shrimp), is made up of twenty body segments grouped into two main body parts, the cephalothorax and the abdomen. Each segment may possess one pair of appendages, although in various groups, these may

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Four extant families of crayfish are described, three in the Northern Hemisphere and one in the Southern Hemisphere. The Southern Hemisphere (Gondwana-distributed) family Parastacidae, with 14 extant genera and two extinct genera, live(d)

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Crayfish are susceptible to infections such as crayfish plagueand to environmental stressors including acidification. In Europe, they are

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In several countries, particularly in Europe, native species of crayfish are under threat by imported variants, particularly the signal crayfish (

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Culinary Use
Crayfish are eaten worldwide. Like other edible crustaceans, only a small portion of the body of a crayfish is

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Fossil records of crayfish older than 30 million years are rare, but fossilised burrows have been found from strata as old as the late Palaeozoic or early Mesozoic. The oldest records of the Parastacidaeare in Australia, and are 115 million years old and the

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