Sea Cucumbers and Brittle Stars Codexery

Sea cucumber

Benthic detritivores with a leathery skin and elongated body.

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Sea cucumbers are echinoderms from the class Holothuroidea.[1] Worldwide, the sea floor is home to benthic marine animals known as holothuroids, of which roughly 1,786 species have been identified.[1] The elongated body and leathery skin of these animals cause them to look similar to a cucumber fruit.[2]

Scientific classification

  1. KingdomAnimalia
  2. PhylumEchinodermata
  3. ClassHolothuroidea

Named by Blainville, 1834

Sources: Wikipedia taxobox: Sea cucumber (CC BY-SA 4.0)

Quick Facts

Class
Holothuroidea
Known species worldwide
about 1,786
Greatest number region
Asia–Pacific region
Smallest species length
3 mm (0.12 in) for Rhabdomolgus ruber

Facts from the source article.

Key facts and history

Most have a soft, cylindrical body ranging from almost spherical to worm-like.[3][4] Sea cucumbers have no true brain, but a ring of neural tissue surrounds the oral cavity.[4] They use cloacal respiration via a pair of "respiratory trees" that draw water in through the anus.[5] The first larval stage is an auricularia, about 1 mm in length, that swims with a band of cilia.[4]

Sea cucumbers serve as detritivores that help recycle nutrients by breaking down detritus.[1] Some species defend themselves by expelling sticky cuvierian tubules or the toxic chemical holothurin.[6] A calcified dermal endoskeleton is present in sea cucumbers, though it is typically reduced to microscopic ossicles.[2] Lengths for holothuroids generally fall between 10 and 30 cm, but some species measure only a few millimeters while others exceed 3 m.[3][4]

Retractile tentacles, which are tube feet that have been heavily modified, encircle the mouth.[4] The typical reproductive method for most sea cucumbers involves the release of sperm and ova into the ocean.[4]

What the cited sources add

The Echinoblog notes that swimming sea cucumbers are often very gelatinous and neutrally buoyant, pushed by currents.[7] Swimming sea cucumbers can maneuver away from underwater mudslides and other physical hazards.[7] These sea cucumbers prefer fresh organic matter that has just fallen onto the sea floor.[7]

References

  1. Wikipedia, "Sea cucumber" (CC BY-SA 4.0), which cites: Paulay, "Holothuroidea", World Register of Marine Species, 2014; "Transcriptome Sequencing and Characterization for the Sea Cucumber Apostichopus japonicus (Selenka, 1867)", PLOS One, 2012; "Transcriptome Sequencing and Characterization for the Sea Cucumber Apostichopus japonicus (Selenka, 1867)", PLOS One, 2012 (original not read by us) en.wikipedia.org
  2. Wikipedia, "Sea cucumber" (CC BY-SA 4.0), which cites: Reich, "Cambrian holothurians? – The early fossil record and evolution of Holothuroidea", Journées Georges Ubaghs, 30–31 January 2006, p. 36–37 (original not read by us) en.wikipedia.org
  3. Wikipedia, "Sea cucumber" (CC BY-SA 4.0), which cites: Walters, "Encyclopedia of Animals", Marks and Spencer p.l.c, 2003, p. 68 (original not read by us) en.wikipedia.org
  4. Wikipedia, "Sea cucumber" (CC BY-SA 4.0), which cites: Barnes, Robert D., "Invertebrate Zoology", Holt-Saunders International, 1982, p. 981–997 (we also read that source) en.wikipedia.org
  5. Wikipedia, "Sea cucumber" (CC BY-SA 4.0), which cites: "Holothurians or sea cucumbers"; Ingram, "Knowing Nature... Cool as a Sea Cucumber", 2006-06-16 (original not read by us) en.wikipedia.org
  6. Wikipedia, "Sea cucumber" (CC BY-SA 4.0), which cites: "Transcriptome Sequencing and Characterization for the Sea Cucumber Apostichopus japonicus (Selenka, 1867)", PLOS One, 2012; Flammang, "Biomechanics of adhesion in sea cucumber Cuvierian tubules (Echinodermata, Holothuroidea)", Integrative and Comparative Biology, 2002-12-01, p. 1107–1115 (original not read by us) en.wikipedia.org
  7. Mah, "Deep-Sea Swimming Sea Cucumbers and the "most bizarre holothurian species in existence" !", The Echinoblog, 2012-09-18. facts only, no text reused. echinoblog.blogspot.com

Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Sea cucumber (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.

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Sources

Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.

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