# Colochirus quadrangularis

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***Colochirus quadrangularis***, commonly known as the **thorny sea cucumber**, is a [species](/source/Species) of [sea cucumber](/source/Holothuroidea) in the [family](/source/Family_(taxonomy)) [Cucumariidae](/source/Cucumariidae). It is found in shallow seas in tropical parts of the [Indo-Pacific](/source/Indo-Pacific) region.

## Description

*Colochirus quadrangularis* is a moderate sized sea cucumber growing to about 10 cm (4 in) in length. The roughly cylindrical body has four longitudinal ridges giving it a square cross section and a flat base. It has irregular, thornlike, soft projections called [papillae](/source/Sea_cucumber#Locomotion) lying along these ridges. The leathery body wall is reinforced by calcareous spike-like structures which in this species include basket-shaped spicules and perforated ellipsoids. There is a ring of large, branched feeding [tentacles](/source/Tentacle) round the mouth. There are three rows of red [tube feet](/source/Tube_feet) on the underside and the body tapers at the posterior end, the anus being surrounded by 5 tooth-like projections. The colour is mainly grey often with pink on the ridges and thorns, and with yellow or reddish tentacles.[2][3][4]

*Colochirus quadrangularis* can be confused with the rather similar pink warty sea cucumber (*[Cercodemas anceps](/source/Cercodemas_anceps)*) but the body of the latter is covered in low, warty protuberances rather than thorny projections.[4]

## Distribution

*Colochirus quadrangularis* is found in the tropical Indo-Pacific region at depths down to about 115 metres (377 ft). Its range extends from East Africa and Madagascar to Malaysia and northern Australia.[1] In Singapore it has unexplained population swings, sometimes being abundant and at other times scarce.[4]

## Biology

*Colochirus quadrangularis* is usually found on the seabed where it clings to [seagrass](/source/Seagrass), [tube worm](/source/Polychaete) cases or other projections with its tube feet. It is a [suspension feeder](/source/Filter_feeder), rearing up its anterior end up and spreading its feathery tentacles to catch [phytoplankton](/source/Phytoplankton) and other organic particles. The tentacles are then retracted one by one and the mouthparts scrape off the food particles.[4] It often has transparent, and almost invisible, [commensal](/source/Commensalism) shrimps (*[Periclimenes](/source/Periclimenes) sp.*) living among its tentacles and on its body wall.[4]

## Uses

*Colochirus quadrangularis* is collected for the aquarium trade but it is difficult to keep in a [reef aquarium](/source/Reef_aquarium) because of its specialist feeding requirements.[4]

## References

1. Paulay, Gustav (2010). "*Colochirus quadrangularis* Troschel, 1846". 213075. Retrieved 2012-02-10.

1. [*Pentacta quadrangularis*](http://species-identification.org/species.php?species_group=nasc&id=93) Marine Species Identification Portal. Retrieved 2012-02-10.

1. [*Colochirus quadrangularis*](http://www.aquaportail.com/fiche-invertebre-1240-colochirus-quadrangularis.html) Aquaportail.com. Retrieved 2012-02-10.

1. [Thorny sea cucumber: *Colochirus quadrangularis*](http://www.wildsingapore.com/wildfacts/echinodermata/holothuroidea/colochirus.htm) Wildsingapore. Retrieved 2012-02-11.

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Adapted from the Wikipedia article [Colochirus quadrangularis](https://en.wikipedia.org/wiki/Colochirus_quadrangularis) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Colochirus_quadrangularis?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.