pseudocoelomate

pseudocoelomate (sōˌdōsēˈləmātˌ) [key], any of a group of invertebrates with a three-layered body that has a fluid-filled body cavity (pseudocoelom) between the endoderm and the mesoderm (the innermost and middle tissue layers). The pseudocoelom is contrasted with the coelom of mollusks, annelid worms, and the more complex animals (including humans and other vertebrates). Pseudocoelomates lack a circulatory system, and the pseudocoelom itself lacks the endothelial lining of a coelom. The hydrostatic pressure of the pseudocoelom gives the body a supportive framework that acts as a skeleton. Nematodes or roundworms (see Nematoda), rotifers (see Rotifera), acanthocephalans (spiny-headed worms), kinorhynchs (see Kinorhyncha) and nematomorphs or horsehair worms (see Nematomorpha) are pseudocoelomates.

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.

More on pseudocoelomate from Fact Monster:

  • aschelminths - aschelminths aschelminths , large assemblage of loosely related, wormlike organisms of extremely ...
  • Priapulida - Priapulida Priapulida, phylum consisting of 17 species of predatory, unsegmented marine worms that ...
  • Kinorhyncha - Kinorhyncha Kinorhyncha , phylum containing about 150 species of tiny pseudocoelomate worms, it is ...
  • Nematomorpha - Nematomorpha Nematomorpha , small (about 230 species) phylum of pseudocoelomates; the horsehair ...
  • Rotifera - Rotifera Rotifera, phylum of predominantly free-living, microscopic, aquatic or semiterrestrial ...

See more Encyclopedia articles on: Zoology: Invertebrates