Bourgueticrinida

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Bourgueticrinida
Haeckel Crinoidea.jpg
Drawing of sea lilies by Haeckel
Scientific classification
Kingdom:
Animalia
Phylum:
Echinodermata
Class:
Crinoidea
Subclass:
Articulata
Order:
Bourgueticrinida
Families [1]

Bathycrinidae
Bourgueticrinidae
Phrynocrinidae
Porphyrocrinidae
Septocrinidae

Contents

Bourgueticrinida is an order of crinoids that typically live deep in the ocean. Members of this order are attached to the seabed by a slender stalk and are known as sea lilies. While other groups of crinoids flourished during the Permian, bourgueticrinids along with other extant orders did not appear until the Triassic, following a mass extinction event in which nearly all crinoids died out.

Taxonomy

Bourgueticrinida has traditionally been viewed as an order of Articulata and a sister taxon to the order Comatulida, the feather stars. A study published in 2011 suggested that it should be renamed Bourgueticrinina and viewed as a suborder of Comatulida. [2]

Characteristics

Artist's impression of several crinoids from the Permian of Western Australia Calceolispongia.JPG
Artist's impression of several crinoids from the Permian of Western Australia

Sea lilies are crinoids with a calyx and five pairs of feather-like arms standing on a long stalk which is retained throughout the animal's life. This stalk is attached to the substrate by means of an enlarged, terminal disc or alternatively by means of several branching, irregular radicular cirri arising from the lowest part of the stem. [3] Although these crinoids are usually sessile, they have been seen to drag themselves across the seabed with the help of their arms. [4] The sea lilies are nearly all found at depths greater than 200 metres (660 ft) although Metacrinus rotundus (a member of a different order) is found off the coast of Japan at a depth of only 100 metres (330 ft). [5]

The ossicles from which the stem is composed are known as columnals. They are discs with a circular, pentagonal, star-shaped or elliptical cross section. The stem is flexible and the columnals are connected to each other with ligaments. At each node where the columnals articulate with each other there may be a whorl of five cirri. These appendages are themselves formed of small ossicles called cirrals and the terminal one is often claw-like. These cirri provide additional anchorage if the stem happens to be in contact with the substrate. [5]

Evolution

The earliest crinoid may have been Echmatocrinus , the fossilised remains of which have been found in the Burgess Shale, but some authorities do not accept it as a crinoid. Bourgueticrinids first appeared in the fossil record during the Triassic period, although other crinoid groups, now extinct, originated in the Ordovician. By the end of the Permian, crinoids were an abundant and very successful group and the columnals are plentiful in many fossiliferous limestone deposits. At that time there were over 6,000 species of sea lily [6] but they were all but extinguished in the Permo-Triassic extinction event. It is believed that only one genus of sea lily survived that occurrence and that all modern crinoids, both the sea lilies and the feather stars, are descended from members of that genus. [7] There are currently about 80 species of bourgueticrinids. [1]

Related Research Articles

Crinoid Class of echinoderms

Crinoids are marine animals that make up the class Crinoidea, one of the classes of the phylum Echinodermata, which also includes the starfish, brittle stars, sea urchins and sea cucumbers. Those crinoids which, in their adult form, are attached to the sea bottom by a stalk are commonly called sea lilies, while the unstalked forms are called feather stars or comatulids, being members of the largest crinoid order, Comatulida.

Articulata (Crinoidea) Subclass of crinoids

Articulata are the only extant subclass of the class Crinoidea. The group includes "sea lilies" and "feather stars". The Articulata are differentiated from the extinct subclasses by their lack of an anal plate in the adult stage and the presence of an entoneural system.

Comasteridae Family of crinoids

Comasteridae is a family of crinoids.

<i>Encrinus</i> Extinct genus of crinoids

Encrinus is an extinct genus of crinoids, and "one of the most famous". It lived during the Late Silurian-Late Triassic, and its fossils have been found in Europe.

Comatulida Order of crinoids

Comatulida is an order of crinoids. Members of this order are known as feather stars and mostly do not have a stalk as adults. The oral surface with the mouth is facing upwards and is surrounded by five, often divided rays with feathery pinnules. Comatulids live on the seabed and on reefs in tropical and temperate waters.

<i>Davidaster rubiginosus</i> Species of crinoid

Davidaster rubiginosus or the orange sea lily is a species of crinoid in the family Comasteridae. At one time it was classified as Nemaster rubiginosa but the World Register of Marine Species has determined that the valid name is Davidaster rubiginosus. It is found on reefs in the tropical western Atlantic and the Caribbean Sea.

<i>Comaster schlegelii</i> Species of crinoid

Comaster schlegelii, the variable bushy feather star, is a crinoid in the family Comasteridae. It was previously classified as Comanthina schlegeli but further research showed that it was better placed in the genus Comaster. It is found on shallow water reefs in the western Pacific Ocean.

<i>Metacrinus rotundus</i> Species of crinoid

Metacrinus rotundus, the Japanese sea lily, is a marine invertebrate, a species of stalked crinoid in the family Isselicrinidae. It is a species found off the west coast of Japan, and is living near the edge of the continental shelf, around 100–150m deep. This is the shallowest species among the extant stalked crinoids.

<i>Oxycomanthus bennetti</i> Species of echinoderm

Oxycomanthus bennetti, the Bennett's feather star, is a species of crinoid belonging to the family Comasteridae. It is found in shallow water in the Indo-Pacific between northern Australia and southeast Asia.

<i>Antedon mediterranea</i> Species of crinoid

Antedon mediterranea is a species of stalkless crinoid in the family Antedonidae, commonly known as the Mediterranean feather star. It is found on the seabed at moderate depths in the Mediterranean Sea. It is a filter feeder and captures plankton with its long feathery arms.

<i>Cenocrinus</i> Genus of crinoids

Cenocrinus is a monotypic genus of stalked crinoids in the family Isselicrinidae. The great West Indian sea lily is the only species in the genus and is found in deep waters in the Caribbean Sea and Gulf of Mexico.

Isocrinida Order of crinoids

Isocrinida is an order of sea lilies which contains four extant families.

<i>Leptometra celtica</i> Species of crinoid

Leptometra celtica is a marine invertebrate and species of crinoid or feather star of the Leptometra genus in the family Antedonidae. It is found in the Atlantic Ocean around the coasts of north west Europe. The presence of L. celtica and L. phalangium is considered to be a good indication of nearby shelf breaks, general bottom currents, and areas of high gross productivity as they are suspension-feeders, hence their proliferation in productive environments.

<i>Florometra serratissima</i> Species of crinoid

Florometra serratissima is a species of crinoid or feather star in the family Antedonidae. It is found off the Pacific coast of North America, usually in deep water.

<i>Endoxocrinus parrae</i> Species of crinoid

Endoxocrinus parrae is a species of stalked crinoids of the family Isselicrinidae. It is the most commonly found isocrinine species in west Atlantic Ocean.

Cyrtocrinida Order of crinoids

Cyrtocrinida is an order of sea lilies which contains two suborders and three families.

<i>Aporometra wilsoni</i> Species of crinoid

Aporometra wilsoni is a marine invertebrate, a species of crinoid or feather star in the family Aporometridae. It is found in shallow water around the coasts of southern Australia.

<i>Notocrinus virilis</i> Species of crinoid

Notocrinus virilis is a marine invertebrate, a species of crinoid or feather star in the family Notocrinidae. It is found in deep water in the Southern Ocean around the coasts of Antarctica and adjacent islands. A sea snail sometimes parasitizes it.

<i>Cenometra bella</i> Species of crinoid

Cenometra bella is a species of crinoids belonging to the genus Cenometra. They can have up to 30 arms and can be of variable colours but are often characterised by a marked contrast between the extending free-arms and the feathery pinnules. This species clings to its support and moves around by its feet-like cirri.

References

  1. 1 2 Messing, Charles (2012). "Bourgueticrinina". WoRMS. World Register of Marine Species . Retrieved 2013-02-11.
  2. ↑ Hess, H; Messing, C. G. (2011) Comatulida. In: Hess H, Messing CG, Ausich WI. Treatise on Invertebrate Paleontology, Part T, Echinodermata 2 Revised, 1633 Crinoidea, vol. 3. University of Kansas Press, Lawrence, Kansas, pp. 70–146.
  3. ↑ Messing, Charles (2012). "Bathycrinidae". WoRMS. World Register of Marine Species . Retrieved 2013-02-11.
  4. ↑ Sea Lily Neocrinus decorus Archived December 31, 2012, at the Wayback Machine
  5. 1 2 Messing, Charles. "Stalk and centrodorsal". Charles Messing's Crinoid Pages. Archived from the original on 2013-01-14. Retrieved 2013-02-11.
  6. ↑ WBS (1996-01-22). "Crinoid Systematics: Articulata". University of California Museum of Paleontology. Retrieved 2013-02-11.
  7. ↑ WBS (1996-01-22). "Crinoidea: Fossil record". University of California Museum of Paleontology. Retrieved 2013-02-11.
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