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crab

crab,crustacean with an enlarged cephalothorax covered by a broad, flat shell called the carapace. Extending from the cephalothorax are the various appendages: five pairs of legs, the first pair bearing claws (or pincers), are attached at the sides; two eyes on short, movable stalks, two short antennules, two longer antennae, and numerous mouthparts are attached at the front; at the rear the tiny abdomen is bent under the cephalothorax.

The abdomen of the female, wider and flatter than that of the male, forms an apronlike structure that continuously circulates water over the eggs that are carried on her underside. The free-swimming larva, which hatches in about two weeks, is easily recognized by the large spine that projects from its carapace. After several molts, the young crab settles to the bottom and begins to take on adult features.

Crabs are chiefly marine, but some are terrestrial for long periods. They are omnivorous; some are scavengers and others predators. Although they are capable of locomotion in all directions, crabs tend to move sideways; swimming crabs have the last pair of legs flattened to form paddles.

The blue crab of the Atlantic coast of the United States is a swimming crab that is much used for food. It is marketed as a soft-shelled crab after it has molted and before the new shell has hardened. Females of the oyster and mussel crabs live inside the shells of bivalve mollusks. Often seen scurrying about near their burrows in muddy banks are the fiddler crabs, the males of which have one much enlarged claw used in defense and in courtship rituals. The sand, or ghost, crabs build burrows high up on the sand into which they seem to vanish. The sluggish, long-legged spider crabs are often disguised by the algae, barnacles, and sea anemones that attach themselves to the carapace. The giant spider crab of Japan, the largest living arthropod, has legs about 4 ft (22 cm) long and a carapace over 1 ft (30 cm) wide. The closely related kelp crabs are found in kelp beds in the Pacific. The name king crab is applied to the largest (up to 20 lb/9 kg) of the edible crabs, species native to the N Pacific and marketed frozen, canned, or fresh; the red king crab has been introduced into the Barents Sea.

True crabs are classified in the phylum Arthropoda, subphylum Crustacea, order Decapoda. Although the many species of true crabs are similar in appearance, DNA evidence suggests that that similarity is a result of convergent evolution among several groups of sometines only distantly related decapods. The horseshoe crab, which also is called by the name king crab, is not a crustacean, and the hermit crab, although a crustacean, is not a true crab.

See J. S. Weis, Walking Sideways: The Remarkable World of Crabs (2012).

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"crab." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 17 Aug. 2017 <http://www.encyclopedia.com>.

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"crab." The Columbia Encyclopedia, 6th ed.. . Retrieved August 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/crab

crab

crab1 / krab/ • n. 1. a crustacean (order Decapoda, class Malacostraca) with a broad carapace, stalked eyes, and five pairs of legs, the first pair of which are modified as pincers. ∎  the flesh of a crab as food. ∎  (the Crab) the zodiacal sign or constellation Cancer. 2. (also crab louse) a louse (Phthirus pubis, family Pediculidae) that infests human body hair, esp. in the genital region, causing extreme irritation. ∎  (crabs) inf. an infestation of crab lice. 3. a machine for lifting heavy weights. • v. 1. [tr.] move sideways or obliquely. 2. [intr.] fish for crabs. DERIVATIVES: crab·ber n. crab·like / -ˌlīk/ adj. & adv. crab2 • n. short for crab apple. crab3 • n. inf. an irritable person. • v. (crabbed , crab·bing ) inf. 1. [intr.] grumble, typically about something petty. 2. [tr.] act so as to spoil: you're trying to crab my act.

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"crab." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 17 Aug. 2017 <http://www.encyclopedia.com>.

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"crab." The Oxford Pocket Dictionary of Current English. . Retrieved August 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/crab-1

crab

crab Flattened, triangular, or oval ten-legged crustacean covered with a hard shell. Primarily marine, some crabs are found in freshwater and a few are terrestrial. Their short abdomen, often called a tail, is bent under. Most have a pair of large foreclaws, a pair of movable eyestalks and a segmented mouth. Crabs usually move sideways. Size: pea-sized to 3m (12ft). Order Decapoda.

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crab

crab Shellfish; Cancer and Carcinus spp.; king crab is Limulus polyphemus. A 100‐g portion (500 g with shell) is a rich source of protein, niacin, zinc, copper, and selenium; a good source of iron; a source of vitamins B2 and B6; contains 400 mg of sodium and 5 g of fat, of which 13% is saturated; supplies 130 kcal (545 kJ).

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"crab." A Dictionary of Food and Nutrition. . Encyclopedia.com. 17 Aug. 2017 <http://www.encyclopedia.com>.

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crab

crab 1 crustacean of the tribe Brachyura. OE. crabba = (M)LG., (M)Du. krabbe, ON. krabbi, rel. to OS. krēƀit, MLG. krēvet, (M)Du. kreeft, OHG. krebiz, krebaz (G. krebs), and to MLG. krabben, ON. krafla scratch, claw.

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"crab." The Concise Oxford Dictionary of English Etymology. . Encyclopedia.com. 17 Aug. 2017 <http://www.encyclopedia.com>.

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crab

crab 2 wild apple. XIV. contemp. with north. scrab (prob. of Scand. orig.; cf. Sw. dial. skrabba wild apple), of which it may be an alteration by assoc. with prec. or CRABBED.

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crab

crab 3 (of hawks) scratch, claw XVI; (sl.) find fault with, ‘pull to pieces’ XIX. — (M)LG. krabben (see CRAB 1).

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Crab

Crab the zodiacal sign or constellation Cancer.

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crab

crabblab, cab, confab, crab, Crabbe, dab, drab, fab, flab, gab, grab, jab, kebab, lab, nab, scab, slab, smash-and-grab, stab, tab •Moab • baobab • rehab • pedicab •minicab • taxicab • Skylab

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