cake urchin

cake urchin

▪ species of echinoderm
      any of the echinoid marine invertebrates of the order Clypeastroida (phylum Echinodermata), in which the body is flattened. The surface is covered with short spines (often furlike) and inconspicuous pedicellariae (pincerlike organs). In many species the hollow, slightly elongated test (internal skeleton), which accommodates the water-vascular system, is symmetrically notched on the edge or has narrow perforations (lunules). The upper surface of the test has a radial, flowerlike arrangement of five porous spaces, called petaloids; the pores permit the extension of tube feet modified for respiration. Tube feet on the underside of the body are used for taking food and may also assist the spines in locomotion.

      Found worldwide in shallow seas, cake urchins burrow in sand and feed on organic particles wafted to the mouth on water currents. They are in turn the prey of other echinoderms and mollusks.

      Cake urchins in which the body is a coinlike, thin-edged disk are called sand dollars (sand dollar), a name sometimes given to cake urchins generally. The test of the common sand dollar (Echinarachnius parma) is often washed up on beaches of North America and Japan. Species with lunules are generally called keyhole urchins. The largest and thinnest cake urchin is the yellow or purple sea pancake (Echinodiscus auritus) of the East African coast.

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Universalium. 2010.

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Look at other dictionaries:

  • Cake urchin — Cake Cake (k[=a]k), n. [OE. cake, kaak; akin to Dan. kage, Sw. & Icel. kaka, D. koek, G.kuchen, OHG. chuocho.] [1913 Webster] 1. A small mass of dough baked; especially, a thin loaf from unleavened dough; as, an oatmeal cake; johnnycake. [1913… …   The Collaborative International Dictionary of English

  • cake urchin — noun Etymology: so called from the disklike shape : a strongly flattened sea urchin (order Exocycloida): as a. : sand dollar b. : keyhole urchin …   Useful english dictionary

  • Cake — (k[=a]k), n. [OE. cake, kaak; akin to Dan. kage, Sw. & Icel. kaka, D. koek, G.kuchen, OHG. chuocho.] [1913 Webster] 1. A small mass of dough baked; especially, a thin loaf from unleavened dough; as, an oatmeal cake; johnnycake. [1913 Webster] 2.… …   The Collaborative International Dictionary of English

  • urchin — /err chin/, n. 1. a mischievous boy. 2. any small boy or youngster. 3. See sea urchin. 4. either of two small rollers covered with card clothing used in conjunction with the cylinder in carding. 5. Chiefly Brit. Dial. a hedgehog. 6. Obs. an elf… …   Universalium

  • Oil cake — Cake Cake (k[=a]k), n. [OE. cake, kaak; akin to Dan. kage, Sw. & Icel. kaka, D. koek, G.kuchen, OHG. chuocho.] [1913 Webster] 1. A small mass of dough baked; especially, a thin loaf from unleavened dough; as, an oatmeal cake; johnnycake. [1913… …   The Collaborative International Dictionary of English

  • To have one's cake dough — Cake Cake (k[=a]k), n. [OE. cake, kaak; akin to Dan. kage, Sw. & Icel. kaka, D. koek, G.kuchen, OHG. chuocho.] [1913 Webster] 1. A small mass of dough baked; especially, a thin loaf from unleavened dough; as, an oatmeal cake; johnnycake. [1913… …   The Collaborative International Dictionary of English

  • sea urchin — 1. any echinoderm of the class Echinoidea, having a somewhat globular or discoid form, and a shell composed of many calcareous plates covered with projecting spines. 2. a tall evergreen shrub or small tree, Hakea laurina, of Australia, having… …   Universalium

  • List of echinoderms of the Houtman Abrolhos — The marine waters of the Houtman Abrolhos, an island chain off the coast of Western Australia, has been recorded as containing 172 species of echinoderm in ?? genera. This extremely high diversity has been attributed to a combination of factors,… …   Wikipedia

  • Sand dollar — Temporal range: 56 –0 Ma …   Wikipedia

  • clypeastroid — I. | ̷ ̷ ̷ ̷|aˌstrȯid adjective Etymology: New Latin Clypeastroida : of or relating to the Clypeastrina II. noun ( s) : one of the Clypeastrina : cake urchin …   Useful english dictionary

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