Some animals that bear the name "crab" are not true crabs. 25 inches wide, to the Japanese spider crab, with a leg span of 8 to 9 feet (Mann). Crabs vary in size from the pea crab, only. About 850 species of crab are freshwater or semi-terrestrial species (Sternberg and Cumberlidge 2001). Crabs are found in all of the world's oceans there are also many freshwater and terrestrial crabs, particularly in tropical regions. There are about 4,500 known species of crabs. They also provide aesthetic benefit to humans, whether for the joy experienced from the wonder of observing their diverse forms and colors, or whether they appeal to other senses via their texture and taste as a food item. Ecologically, they are integral to food webs, both as a consumer of animals and plants, and as a popular prey for many birds, fish, and mammals. Economically and nutritionally, crabs are a popular food item. Crabs typically are characterized by the first pair of the five pairs of appendages being modified into chelae (claws), a thick exoskeleton, and an upper body shield or carapace that is generally broad, hard, and flattened.Ĭrabs offer important benefits to human beings. ![]() As members of the Brachyura taxon, crabs typically have a very short "tail" or the abdomen is entirely hidden under the thorax (( Greek: brachy = short, ura = tail). An asterisk (*) marks the crabs included in the clade Thoracotremata.Ĭrabs are decapod crustaceans of the Brachyura infraorder or division.Īs members of the order Decapoda, which also includes crayfish, lobsters, prawns, and shrimp, crabs have ten legs: the last five pairs of the eight pairs of thoracic appendages characteristic of crustaceans.
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