Cydippida

Article By:

Madin, Laurence P. Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts.

Last reviewed:December 2019

DOI:https://doi.org/10.1036/1097-8542.177300

The largest order of the phylum Ctenophora, comprising 5 families (Bathyctenidae, Haeckelidae, Lampeidae, Mertensidae and Pleurobrachiidae) and 11 genera. The body of cydippids is usually globular or cylindrical in shape (see illustration); sizes range from a few millimeters to about 15 cm (6 in.). Most cydippids are colorless and transparent, but some deep-sea species are pigmented dark red. The comb rows are of equal length and the eight meridional canals lying beneath them end blindly at the oral end. Adult cydippids retain the larval morphology common to all ctenophores (except Beroida) and are usually thought to be the most primitive order. All forms have two main tentacles, which have side branches (tentilla) in some species. Cydippids catch prey on the outstretched tentacles, contracting them to bring it to the mouth. In three families (Bathyctenidae, Haeckelidae and Lampeidae), the tentacles emerge from the body near the oral end; these cydippids have extensile mouths and catch large gelatinous animals. In the Pleurobrachiidae and Mertensidae, the tentacles exit near the aboral end, have numerous side branches and catch mostly small crustacean prey. The well-known genus Pleurobrachia is widely distributed in temperate coastal waters and estuaries, where it can be a major predator of copepods and larval fish. Many other species of cydippids occur in oceanic waters, from the surface to mesopelagic depths. See also: Beroida; Ctenophora

The content above is only an excerpt.