tusk shell

tusk shell

also called  elephant's tusk,  elephant's tooth , or  tooth shell 

      any of several marine mollusks of the class Scaphopoda. There are four genera of tusk shells (Dentalium is typical and most common) and more than 350 species. Most tusk shells live in fairly deep water, sometimes to depths of about 4,000 metres (13,000 feet); many deep-sea species are cosmopolitan in distribution.

      Tusk shells are elongated, bilaterally symmetrical (i.e., the external halves are mirror images of one another) animals with a tubular, tusklike shell, open at both ends. The animals are encased in a tubular mantle and breathe through the body surface. At the anterior (front), larger end of the shell is an extensible foot adapted for digging and an imperfectly developed head with slender tentacles, the captacula, that serve as sensory and food-catching organs. The anterior end is usually buried in the sea bottom. The posterior end admits water for respiration and discharges wastes. Tusk shells feed upon such small organisms as protozoans of the order Forminifera and young bivalves. Sexes are separate, and the eggs develop into free-swimming trochophore larvae.

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Universalium. 2010.

Look at other dictionaries:

  • tusk-shell — Tusk Tusk, n. [OE. tusk, the same word as tusch, AS. tusc. See {Tush} a tooth.] 1. (Zo[ o]l.) One of the elongated incisor or canine teeth of the wild boar, elephant, etc.; hence, any long, protruding tooth. [1913 Webster] 2. (Zo[ o]l.) A… …   The Collaborative International Dictionary of English

  • Tusk-shell — n. (Zo[ o]l.) See 2d {Tusk}, n., 2. [1913 Webster] …   The Collaborative International Dictionary of English

  • Tusk shell — The tusk shells or scaphopods are a class of marine mollusks which vary in size from very small to medium sized. The scientific name of this class is Scaphopoda, meaning shovel footed . These mollusks live on soft substrates offshore (usually not …   Wikipedia

  • tusk shell — noun any of various seashore mollusks having a tapering tubular shell open at each end and a foot pointed like a spade for burrowing • Syn: ↑tooth shell • Hypernyms: ↑scaphopod * * * noun : tooth shell * * * tusk shell noun Th …   Useful english dictionary

  • tusk shell — noun a burrowing mollusc with a slender tusk shaped shell which is open at both ends. [Dentalium and other genera, class Scaphopoda.] …   English new terms dictionary

  • tusk shell. — See tooth shell. [1860 65, Amer.] * * * …   Universalium

  • tusk shell. — See tooth shell. [1860 65, Amer.] …   Useful english dictionary

  • tusk shell — noun any of the marine mollusks of the class Scaphopoda, which look similar to elephant tusks. Syn: scaphopod …   Wiktionary

  • elephant's-tusk shell — noun see elephant s tusk …   Useful english dictionary

  • Tusk (disambiguation) — Tusk can refer to a number of things:*A tusk is an extremely long tooth, possessed by certain mammals, that sticks out of the mouth when it s closed. It is the source of ivory. * tusk is the pseudonym of Eberhard Koebel, a German writer and… …   Wikipedia

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