Desmoscolecida is an order of marine nematodes.WoRMS - World Register of Marine Species - Desmoscolecida
/ref> In a worm of this order, the body tapers towards each end and is marked by a number of well-defined ridges. Their number varies in the different species. The head bears four movable

seta In biology, setae (singular seta ; from the Latin word for " bristle") are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Annelid setae are stiff bristles present on the body. ...

e, and some of the ridges bear a pair either dorsally or ventrally. Two pigment spots between the fourth and fifth ridges are regarded as eyes. The Desmoscolecida move by looping their bodies like geometrid caterpillars or leeches, as well as by creeping on their setae. The mouth is terminal, and leads into a muscular

oesophagus The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to th ...

which opens into a straight intestine terminating in an anus, which is said to be dorsal in position. The sexes are distinct. The testis is single, and its duct opens into the intestine and is provided with two chitinous

spicule Spicules are any of various small needle-like anatomical structures occurring in organisms Spicule may also refer to: *Spicule (sponge), small skeletal elements of sea sponges *Spicule (nematode), reproductive structures found in male nematodes ( ...

s. The ovary is also single, opening independently and anterior to the anus. The nervous system is as yet unknown. Genera include '' Desmoscolex'', '' Greeffiella'', and '' Tricoma''.

References

* Paolo Panceri, ''Atti dell'Accademia Pontaniana'' (previously, ''Atti della Società pontaniana di Napoli''). vii. (1878) * Richard Greeff, ''

Archiv für Naturgeschichte ''Archiv für Naturgeschichte'' was a German-language journal for natural history. It was founded by A. F. A. Wiegmann in 1835. The journal was published in Berlin from 1835 to 1926. There were 92 published volumes. From 1912 to 1926 each volume w ...

'' 35 (i.) (1869), p. 112. (A. E. S.) Nematode orders Chromadorea {{Chromadorea-stub