Sea Cucumbers and Brittle Stars Codexery

Brittle star

Echinoderms with five serpent-like arms, found worldwide in marine habitats.

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Brittle stars are echinoderms with five slender arms sharply set off from a central disk, and they are the most diverse living echinoderm group.[1][2] Over 2,000 species exist today, with more than 1,200 found in deep waters deeper than 200 meters.[3]

Scientific classification

  1. KingdomAnimalia
  2. PhylumEchinodermata
  3. ClassOphiuroidea

Named by Gray, 1840

Sources: Wikipedia taxobox: Brittle star (CC BY-SA 4.0)

Quick Facts

Type species
Ophiura ophiura

Facts from the source article.

Key facts and history

The ophiuroid lineage diverged in the Early Ordovician.[4] Brittle stars live in all marine provinces, from poles to tropics, and some tolerate brackish water.[4][5] Their skeleton is made of fused calcite ossicles forming armor plates.[2] The central disk contains all viscera, and the mouth on the underside has five toothed jaws.[2]

Most species have separate sexes, and fertilization is usually external.[2] Some brittle stars reproduce asexually by fission, splitting the disk in half.[6] The cilia-lined bursae, which are sacs located between the arm bases on the underside of the disk, are responsible for both gas exchange and excretion.[2] Research on the West Indian brittle star Ophiocomella ophiactoides shows that its population relies primarily on fission, a form of asexual reproduction, rather than sexual reproduction.[7]

Sexual maturity in brittle stars is typically reached at two to three years of age, and their maximum lifespan is about five years.[8]

What the cited sources add

The Echinoblog notes that brittle stars are the most diverse living echinoderms, with 2,064 recognized species as of 2013.[1] The Ophiuridae family includes 344 species.[1] Brittle stars live under rocks, in mud, on corals, and even on jellyfish.[1] The Echinoblog explains that "brittle stars" refers to conventional ophiuroids, while "basket stars" are highly branched types.[1]

Barnes' "Invertebrate Zoology" states that the madreporite is usually inside a jaw plate, not on the upper side.[2][9] The same source notes that ophiuroids have no eyes but sense chemicals, touch, and light through nerve endings.[2]

References

  1. Mah, "Brittle Star Diversity! How many are there and where do they live?", The Echinoblog, 28 January 2014. facts only, no text reused. echinoblog.blogspot.fr
  2. Wikipedia, "Brittle star" (CC BY-SA 4.0), which cites: Barnes, Robert D., "Invertebrate Zoology", Holt-Saunders International, 1982, p. 957–959 (we also read that source) en.wikipedia.org
  3. Wikipedia, "Brittle star" (CC BY-SA 4.0), which cites: Stöhr, "Global diversity of brittle stars (Echinodermata: Ophiuroidea)", PLOS ONE, 2012; Stöhr, "Global diversity of brittle stars (Echinodermata: Ophiuroidea)", PLOS ONE, 2012 (original not read by us) en.wikipedia.org
  4. Wikipedia, "Brittle star" (CC BY-SA 4.0), which cites: Mikuláš, "First occurrence of a "brittlestar bed" (Echinodermata, Ophiuroidea) in Bohemia (Ordovician, Czech Republic)", Bulletin of the Czech Geological Survey, 1995, p. 17–24; Stöhr, "Global diversity of brittle stars (Echinodermata: Ophiuroidea)", PLOS ONE, 2012; Cousteau, "The Human, The Orchid and The Octopus", Bloomsbury, 2007, p. 205–206 (original not read by us) en.wikipedia.org
  5. Wikipedia, "Brittle star" (CC BY-SA 4.0), which cites: Turner, "Salinity Tolerance of the Brackish-Water Echinoderm Ophiophragmus filograneus (Ophiuroidea)", Marine Ecology Progress Series, 30 April 1980, p. 249–256 (original not read by us) en.wikipedia.org
  6. Wikipedia, "Brittle star" (CC BY-SA 4.0), which cites: McGovern, "Patterns of sexual and asexual reproduction in the brittle star Ophiactis savignyi in the Florida Keys", Marine Ecology Progress Series, 2002-04-05, p. 119–126 (original not read by us) en.wikipedia.org
  7. Wikipedia, "Brittle star" (CC BY-SA 4.0), which cites: Mladenov, Philip V., "Asexual reproduction in the west Indian brittle star Ophiocomella ophiactoides (H.L. Clark) (Echinodermata: Ophiuroidea)", Journal of Experimental Marine Biology and Ecology, 1983, p. 1–23 (original not read by us) en.wikipedia.org
  8. Wikipedia, "Brittle star" (CC BY-SA 4.0), which cites: "Common brittlestar | the Wildlife Trusts" (original not read by us) en.wikipedia.org
  9. Open Library record, ISBN 0030567475 ("Invertebrate zoology"). CC0 (metadata); book content not read. openlibrary.org

Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Brittle star (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.

Related entries

Named in this entry

Ophiura ophiuraOphiuridaeCalciteAsexual reproduction

More in Brittle Stars

Basket starMelusinasterOphiocanops fugiensOphiuridaPhrynophiuridaAcrocnidaAstrophytonGorgonocephalusOphioderma (echinoderm)OphiolepisOphiuraOphiozonella depressa

Elsewhere in Sea Cucumbers and Brittle Stars

Sea cucumber · Sea CucumbersPsychropotes · Sea CucumbersEuapta lappa · Sea CucumbersPsychropotidae · Sea CucumbersHolothuria glaberrima · Sea CucumbersHolothuria whitmaei · Sea Cucumbers

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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