Sipunculus nudus
From Wikipedia, the free encyclopedia
| Sipunculus nudus | |
|---|---|
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Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Annelida |
| Class: | Sipuncula |
| Order: | Golfingiida |
| Family: | Sipunculidae |
| Genus: | Sipunculus |
| Species: | S. nudus |
| Binomial name | |
| Sipunculus nudus Linnaeus, 1766 | |
Sipunculus nudus is a cosmopolitan species of unsegmented marine worm of the class Sipuncula, also known as peanut worms.
As in all peanut worms, the body of S. nudus consists of a sac-like portion called the trunk and an eversible proboscis called the introvert. The mouth is located at the anterior end of the introvert and is surrounded by a group of tentacles. The body of the adult worm is around 15 centimetres (5.9 in) in length but can reach up to 25 cm (9.8 in) in some cases, of which about 3.5 centimetres (1.4 in) to 6 centimetres (2.4 in) correspond to the introvert.[1]
The epidermis contains a series of longitudinal coelomic canals that are connected to the main coelomic cavity by pores. Below the epidermis there are circular muscles surrounding the body which, as the coelomic canals, are marked on the surface, making the animal's surface be marked by rectangular ridges.[1]
Sipunculus nudus in Pula, Croatia
Sipunculus nudus (front end) in Pula, Croatia
Sipunculus nudus (body texture) in Pula, Croatia
Distribution
Sipunculus nudus is commonly found on subtidal zones of sandy shores to seabeds 900 metres (3,000 ft) deep in temperate or tropical waters worldwide. The worm hides in sand burrows which it makes by itself during the day and may extend its tentacles out of the burrow to feed at night. Its diet consists of plant or animal tissue fragments and any surrounding sand it may ingest with it.
Recent research indicates that it is a complex of similar species around the world rather than one species, with at least "five distinct lineages identified by phylogenetic analyses".[2]
