Choanoflagellate: Difference between revisions
Josh Grosse (talk | contribs) mNo edit summary |
Josh Grosse (talk | contribs) mNo edit summary |
||
Line 14: | Line 14: | ||
The [[choanocyte]]s of [[sponge]]s have the same basic structure as choanoflagellates. Collared cells are occasionally found in a few other animal groups, such as [[flatworm]]s. |
The [[choanocyte]]s of [[sponge]]s have the same basic structure as choanoflagellates. Collared cells are occasionally found in a few other animal groups, such as [[flatworm]]s. |
||
[[Category:Protista]] |
[[Category:Protista]] |
||
[[fr:Choanoflagellé]] |
Revision as of 18:26, 2 November 2004
Template:Taxobox begin Template:Taxobox begin placement Template:Taxobox regnum entry Template:Taxobox phylum entry Template:Taxobox classis entry Template:Taxobox end placement Template:Taxobox end The choanoflagellates are a group of flagellate protozoa. They are considered to be the closest relatives of the animals, and in particular may be the direct ancestors of sponges.
Each choanoflagellate has a single flagellum, surrounded by a ring of hairlike protrusions called microvilli, forming a cylindrical or conical collar (choanos in Greek). The flagellum pulls water through the collar, and small food particles are captured by the microvilli and ingested. It also pushes free-swimming cells along, as in animal sperm, whereas most other flagellates are pulled by their flagella.
Most choanoflagellates are sessile, with a stalk opposite the flagellum. A number of species are colonial, usually taking the form of a cluster of cells on a single stalk. Of special note is Proterospongia, which takes the form of a glob of cells, of which the external cells are typical flagellates with collars, but the internal cells are non-motile.
The choanocytes of sponges have the same basic structure as choanoflagellates. Collared cells are occasionally found in a few other animal groups, such as flatworms.