gastrotrich

gastrotrich
gastrotrichan /gas tro"tri keuhn/, adj.
/gas"treuh trik/, n.
any of the microscopic, multicellular animals of the class or phylum Gastrotricha, of fresh or salt waters, characterized by bands of cilia on the ventral surface of the bottle-shaped or ribbony body and by a protrusible feeding apparatus at the mouth.
[1935-40; < NL Gastrotricha, equiv. to gastro- GASTRO- + Gk -tricha neut. pl. of -trichos -haired, adj. deriv. of thríx hair]

* * *

      any of about 500 species of the phylum Gastrotricha, a group of microscopic aquatic invertebrates that live in the spaces between sand grains and soil particles and on the outer coverings of aquatic plants and animals. They occur in salt water and freshwater and also on sandy seashores.

      The gastrotrich body, which ranges in size from 0.1 to 1.5 millimetres (0.004 to 0.06 inch), is covered by a cuticle that is often scaly and spiny. The head is swollen and lobelike. Adhesive tubules are used for anchorage. Cilia—especially on the head and on the ventral, or bottom, surface—are used for locomotion.

      Bacteria, organic debris, and certain protozoans (diatoms) are ingested by a sucking muscular pharynx, which leads to the intestine. Many species are hermaphroditic (i.e., reproductive organs of both sexes occur in the same individual). One group, Chaetonotoidea, has only parthenogenetic females (i.e., they produce unfertilized eggs that, in turn, produce females). Two types of eggs are known for freshwater gastrotrichs: tachyblastic eggs, which develop immediately, and opsiblastic eggs, which remain inactive for long periods and can survive dry and freezing conditions.

      Gastrotrichs were formerly placed within a phylum of animals called the Aschelminthes. The similarities among aschelminths are now understood to be the result of independent evolution in comparable habitats rather than close evolutionary relationships. Many aschelminth groups have been raised to the level of independent phyla.

* * *


Universalium. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • gastrotrich — [gas′trō trik] n. [< ModL Gastrotricha < GASTRO + tricha, ciliate creatures < Gr neut. pl. of trichos, haired < thrix (gen. trichos), hair] any of a phylum (Gastrotricha) of minute, aquatic, wormlike animals that swim by means of… …   English World dictionary

  • Gastrotrich — Taxobox name = Gastrotrichs image width = 250px image caption = Darkfield photograph of a gastrotrich. regnum = Animalia subregnum = Eumetazoa unranked phylum = Bilateria superphylum = Platyzoa phylum = Gastrotricha phylum authority =… …   Wikipedia

  • gastrotrich — noun Etymology: ultimately from Greek gastr + trich , thrix hair more at trich Date: 1940 any of a phylum (Gastrotricha) of minute aquatic pseudocoelomate animals that usually have a spiny or scaly cuticle and cilia on the ventral surface …   New Collegiate Dictionary

  • gastrotrich — noun A microscopic aquatic animal of the phylum Gastrotricha, with a worm like body and cilia …   Wiktionary

  • gastrotrich — gas·tro·trich …   English syllables

  • gastrotrich — gas•tro•trich [[t]ˈgæs trə trɪk[/t]] n. ivt any tiny aquatic animal of the phylum Gastrotricha, having a long, sometimes bottle shaped body, with cilia on the underside • Etymology: 1935–40; < NL Gastrotricha < Gk gastro gastro + tricha,… …   From formal English to slang

  • gastrotrich — /ˈgæstrətrɪk/ (say gastruhtrik) noun one of the microscopic multicellular worms belonging to the phylum Gastrotricha, having bands of cilia on the ventral side of the body …  

  • gastrotrich — ˈgastrə.ˌtrik noun ( s) Etymology: New Latin Gastrotricha : an animal of the group Gastrotricha * * * gastrotrichan /gas tro tri keuhn/, adj. /gas treuh trik/, n. any of the microscopic, multicellular animals of the class or phylum Gastrotr …   Useful english dictionary

  • Heard Island and McDonald Islands — Heard Island Nickname: HIMI Satellite image of the southern tip of Heard Island. Cape Arkona is seen on the left side of the image, with Lied Glacier just above and Gotley Glacier just below. Big Ben Volcano and Mawson Peak are seen at the lower… …   Wikipedia

  • Benthos — are the organisms which live on, in, or near the seabed, also known as the benthic zone. [http://www.caml.aq/benthos/index.html Benthos] from the Census of Antarctic Marine Life website] They live in or near marine sedimentary environments, from… …   Wikipedia

Share the article and excerpts

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