Saturday, June 18, 2011
A zooid or zoöid /ˈzoʊ.ɔɪd/ is a single animal that is part of a colonial animal. The zooids can either be directly connected by tissue (e.g. corals, Catenulida,Siphonophorae or Ectoprocta) or share a common exoskeleton (e.g. Bryozoa or Pterobranchia). The colonial organism as a whole is called a zoon /ˈzoʊ.ɒn/, plural zoa.
The term zooid has historically also been used for an organic cell or organized body that has independent movement within a living organism, especially a motile gamete such as a spermatozoon (in the case of algae now zoid), or an independent animal-like organism produced asexually, as by budding or fission.