polychaete


polychaete
/pol"i keet'/, n.
1. any annelid of the class Polychaeta, having unsegmented swimming appendages with many setae or bristles.
adj.
2. Also, polychaetous. belonging or pertaining to the Polychaeta.
[1885-90; < NL Polychaeta < Gk polychaítes having much hair. See POLY-, CHAETA]

* * *

Any of about 5,400 species of marine worms of the annelid class Polychaeta, having a segmented body with many setae (bristles) on each segment.

Species, often brightly coloured, range from less than 1 in. (2.5 cm) to about 10 ft (3 m) long. Most body segments bear two bristly parapodia (lobelike outgrowths). The head has short sensory projections and tentacles. Adults may be free-swimming or sedentary; larvae are free-swimming. Found worldwide, polychaetes are important for turning over sediment on the ocean bottom. One species, the bloodworm, is a popular saltwater fish bait. See also tube worm.

* * *

      any worm of the class Polychaeta (phylum Annelida). About 8,000 living species are known. Polychaetes, which include rag worms, lugworms, bloodworms, sea mice, and others, are marine worms notable for well-defined segmentation of the body. Unique among annelids, most polychaete body segments bear a pair of parapodia (flat, lobelike outgrowths) with setae, or tiny bristles. Polychaetes vary in size from a few millimetres to about 3 m (10 feet) and are divided informally into two groups; the errantia, or free-moving forms, and sedentaria, or tube-dwelling forms.

      The head has short sensory projections (palps) and tentacles. The body is often brightly coloured. The diet consists of minute aquatic plants and animals in some species, while others are purely carnivorous.

      The sexes are usually separate; sperm and eggs are discharged directly into the water, where fertilization occurs. Larvae are ciliated and free-swimming. As in some mollusk species, the early larvae are trochophores. Some polychaete species are hermaphroditic (i.e., the functional reproductive organs of both sexes are present in one individual); other species reproduce by budding, in which a portion of an adult's body breaks away to form a new individual.

      Polychaetes play an important role in turning over bottom sediments in the sea. The palolo worm (q.v.) is used as human food in areas of the South Pacific where it swarms in great abundance at breeding time. Other species are used by humans as bait for fishing.

* * *


Universalium. 2010.

Look at other dictionaries:

  • polychaete — [päl′i kēt΄] n. [< ModL Polychaeta < Gr polychaitēs, with much hair < poly , POLY + chaitē, hair] any of a class (Polychaeta) of mostly marine, annelid worms, having on most segments a pair of fleshy, leglike appendages bearing numerous… …   English World dictionary

  • Polychaete — Taxobox fossil range = Cambrian (or earlier?) present name = Polychaetes image width = 250px image caption = A variety of marine worms : plate from Das Meer by M. J. Schleiden (1804–1881). regnum = Animalia phylum = Annelida classis = Polychaeta… …   Wikipedia

  • polychaete — noun Etymology: ultimately from Greek polychaitēs having much hair, from poly + chaitē long hair Date: 1896 any of a class (Polychaeta) of chiefly marine annelid worms (as clam worms) usually with paired segmental appendages, separate sexes, and… …   New Collegiate Dictionary

  • Polychaete — Polychaeta Polychaeta (Polychètes) …   Wikipédia en Français

  • polychaete — [ pɒlɪki:t] noun Zoology a marine worm of the order Polychaeta; a bristle worm. Origin from mod. L. Polychaeta, from Gk polu many + khaitē mane …   English new terms dictionary

  • polychaete — poly·chaete …   English syllables

  • polychaete — pol•y•chaete [[t]ˈpɒl ɪˌkit[/t]] n. 1) ivt any of various marine annelid worms of the class Polychaeta, having regularly paired body bristles and often other appendages 2) ivt Also, pol y•chae′tous. belonging or pertaining to the Polychaeta •… …   From formal English to slang

  • polychaete — /ˈpɒlikit/ (say poleekeet) noun 1. any of the Polychaeta, a group or division of annelids having unsegmented swimming appendages (parapodia) with many chaetae or bristles, and including most of the common marine worms. –adjective Also,… …   Australian English dictionary

  • polychaete —   a.,n. (pertaining to) marine worm.    ♦ polychaetous, a …   Dictionary of difficult words

  • polychaete — n. any aquatic annelid worm of the class Polychaeta, including lugworms and ragworms, having numerous bristles on the fleshy lobes of each body segment. Derivatives: polychaetan adj. polychaetous adj. * * * /pol i keet /, n. 1. any annelid of the …   Useful english dictionary


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.