Editing Sea cucumber (section)

=== Diet ===
Holothuroidea are generally [[scavenger]]s, feeding on debris in the [[benthic zone]] of the ocean. Exceptions include some [[Pelagic zone|pelagic]] cucumbers and the species ''Rynkatorpa pawsoni'', which has a [[commensalism|commensal]] relationship with deep-sea [[anglerfish]].<ref>{{cite book|last1=Brusca|first1= R.C.|last2=Brusca|first2= G.J.| title=Invertebrates|url=https://archive.org/details/invertebrates0000brus|url-access=registration|publisher= SinauerAssociates|location= Massachusetts|year=1990|isbn=978-0-87893-097-5}}</ref> The [[diet (nutrition)|diet]] of most cucumbers consists of [[plankton]] and decaying organic matter found in the sea. Some sea cucumbers position themselves in [[Ocean current|currents]] and catch food that flows by with their open tentacles. They also sift through the bottom [[sediment]]s using their tentacles. Other species can dig into bottom silt or sand until they are completely buried. They then extrude their feeding tentacles, ready to withdraw at any hint of danger.

In the South Pacific, sea cucumbers may be found in densities of {{convert|40|/m2|/sqft|abbr=on|disp=preunit|individuals}}. These populations can process {{convert|19|kg/m2|lb/sqft}} of sediment per year.<ref>{{cite book |title=Coral Reefs: Cities Under TheSeas|last=Murphy |first=Richard C.|year=2002 |page=36|isbn=978-0-87850-138-0 |publisher=The Darwin Press, Inc.}}</ref>

The shape of the tentacles is generally adapted to the diet, and to the size of the particles to be ingested: the filter-feeding species mostly have complex arborescent tentacles, intended to maximize the surface area available for filtering, while the species feeding on the substratum will more often need digitate tentacles to sort out the nutritional material; the detritivore species living on fine sand or mud more often need shorter "peltate" tentacles, shaped like shovels. A single specimen can swallow more than {{convert|45|kg}} of sediment a year, and their excellent digestive capacities allow them to reject a finer, purer and homogeneous sediment. Therefore, sea cucumbers play a major role in the biological processing of the sea bed (bioturbation, purge, homogenization of the substratum etc.).

<gallery style="text-align:center;" mode="packed">
Image:Euapta godeffroyi, détail.jpg|The mouth of ''[[Euapta godeffroyi]]'', showing pinnate tentacles.
Image:Apostichopus californicus.004 - Aquarium Finisterrae.jpg|Mouth of ''[[Holothuria]] sp.'', showing peltate tentacles.
Image:Cucumaria main.jpg|Mouth of ''[[Cucumaria miniata]]'', with dendritic tentacles, for filtering the water.
Image:Holothurie sp..jpg|Faeces of a holothuroid. This participates in sediment homogenization and purification.
</gallery>