Temporal range:
Crinoid on the reef of Batu Moncho Island.JPG
Crinoid on the reef of Batu Moncho Island, Indonesia
Scientific classification e
Kingdom: Animalia
Phylum: Echinodermata
Subphylum: Crinozoa
Class: Crinoidea
Miller, 1821[2]
Major groups

Crinoids are marine animals that make up the class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their juvenile form are commonly called sea lilies, while the unstalked forms, called feather stars or comatulids, are members of the largest crinoid order, Comatulida. Crinoids are echinoderms in the phylum Echinodermata, which also includes the starfish, brittle stars, sea urchins and sea cucumbers.[3] They live in both shallow water[4] and in depths as great as 9,000 meters (30,000 ft).[5]

Adult crinoids are characterised by having the mouth located on the upper surface. This is surrounded by feeding arms, and is linked to a U-shaped gut, with the anus being located on the oral disc near the mouth. Although the basic echinoderm pattern of fivefold symmetry can be recognised, in most crinoids the five arms are subdivided into ten or more. These have feathery pinnules and are spread wide to gather planktonic particles from the water. At some stage in their lives, most crinoids have a stem used to attach themselves to the substrate, but many live attached only as juveniles and become free-swimming as adults.

There are only about 700 living species of crinoid,[6] but the class was much more abundant and diverse in the past. Some thick limestone beds dating to the mid-Paleozoic to Jurassic eras are almost entirely made up of disarticulated crinoid fragments.[7][8][9]

  1. ^ Zamora, Samuel; Rahman, Imran A.; Ausich, William I. (2015). "Palaeogeographic implications of a new iocrinid crinoid (Disparida) from the Ordovician (Darriwillian) of Morocco". PeerJ. 3: e1450. doi:10.7717/peerj.1450. PMC 4675106. PMID 26664800.
  2. ^ Hansson, Hans (2012). "Crinoidea". WoRMS. World Register of Marine Species. Retrieved 2013-01-30.
  3. ^ Cite error: The named reference Ruppert was invoked but never defined (see the help page).
  4. ^ Zmarzly, D.L. (1985). "The Shallow-Water Crinoid Fauna of Kwajalein Atoll, Marshall Islands: Ecological Observations, Interatoll Comparisons, and Zoogeographic Affinities". Pacific Science. 39: 340–358. hdl:10125/941.
  5. ^ Oji, T.; Ogawa, Y.; Hunter, A. W. & Kitazawa, K. (2009). "Discovery of Dense Aggregations of Stalked Crinoids in Izu-Ogasawara Trench, Japan". Zoological Science. 26 (6): 406–408. doi:10.2108/zsj.26.406. PMID 19583499. S2CID 5991969.
  6. ^ Reproduction and Development in Echinodermata and Prochordata
  7. ^ Lucia, F. Jerry (1962). "Diagenesis of a Crinoidal Sediment". SEPM Journal of Sedimentary Research. 32: 848–865. doi:10.1306/74D70D8F-2B21-11D7-8648000102C1865D.
  8. ^ Blyth Cain, J. D. (September 1968). "Aspects of the depositional environment and palaeoecology of crinoidal limestones". Scottish Journal of Geology. 4 (3): 191–208. doi:10.1144/sjg04030191. S2CID 219538295.
  9. ^ Jach, Renata (April 2005). "Storm-dominated deposition of the Lower Jurassic crinoidal limestones in the Krížna unit, Western Tatra Mountains, Poland". Facies. 50 (3–4): 561–572. doi:10.1007/s10347-004-0028-3. S2CID 128947091.

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