''Cenocrinus'' is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of stalked

crinoid Crinoids are marine animals that make up the class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their adult form are commonly called sea lilies, while the unstalked forms are called feather stars or comatulids, which are ...

s in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Isselicrinidae Isselicrinidae is one of four extant families of crinoids in the order Isocrinida. Subfamilies and genera * subfamily Diplocrininae Roux, 1981 ** genus '' Cenocrinus'' Thomson, 1864 -- 1 species ** genus '' Endoxocrinus'' AH Clark, 1908 -- 5 s ...

. The great West Indian sea lily (''Cenocrinus asterius'') is the only species in the genus and is found in deep waters in the

Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lanmè Karayib; jam, Kiaribiyan Sii; nl, Caraïbische Zee; pap, Laman Karibe) is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico ...

and

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United ...

Description

Like other sea lilies, ''Cenocrinus asterius'' has a crown consisting of a calyx surrounded by feathery arms splayed out to create a filtration fan. The crown is supported by a long slender stem which is attached to the substrate at its base. The stem is semi-rigid but flexible and is made up of disc-shaped ossicles known as columnals, joined together by ligaments. At each node between the columnals there is a whorl of five

cirri Giovanni Battista Cirri (1 October 1724 – 11 June 1808) was an Italian cellist and composer in the 18th century. Biography Cirri was born in Forlì in the Emilia-Romagna Region of Italy. He had his first musical training with his brother ...

. These are also articulated and are tipped with claws and when the cirri come into contact with other objects, they cling to them and help stabilise the sea lily and keep it upright.

Distribution

''Cenocrinus asterius'' is found in the Caribbean Sea, the Gulf of Mexico and off the coast of Mexico.

Biology

''Cenocrinus asterius'' lives on areas of the seabed with strong currents at depths of more than . This enables it to maximise the capture of food particles by the sticky

tube feet Tube feet (technically podia) are small active tubular projections on the oral face of an echinoderm, whether the arms of a starfish, or the undersides of sea urchins, sand dollars and sea cucumbers; they are more discreet though present on br ...

on its arms without them being fouled by the collection of its own faecal matter. ''Cenocrinus asterius'' has been studied in a laboratory flow tank where it was found that, with the base of the stem detached, it could move itself along the substrate and climb objects. It took as long as twenty four hours to manoeuvre itself into its usual, near vertical posture and reattach itself. In its natural surroundings, it may be assisted in this process by the hydrodynamic lift provided by a strong current in elevating its fan of arms. In studies by cameras mounted on submersibles, it has been found that sea lilies can drag themselves along the seabed by their arms. In the case of ''Cenocrinus asterius'', this may be in response to attack by the sea urchin ''

Calocidaris micans ''Calocidaris micans'' is a species of sea urchins of the family Cidaridae. Their armour is covered with spines. ''Calocidaris micans'' was first scientifically described in 1903 by Ole Mortensen Ole Henrik Mortensen (born 29 January 1958) i ...

'' which has been shown to feed on live crinoids. Although the rate of movement was slow, it was sufficiently fast to outpace the echinoid.

Autotomy Autotomy (from the Greek ''auto-'', "self-" and ''tome'', "severing", αὐτοτομία) or self-amputation, is the behaviour whereby an animal sheds or discards one or more of its own appendages, usually as a self-defense mechanism to elude ...

of the stalk may also take place in an effort to evade the

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

. The sexes are separate in ''Cenocrinus asterius''. Like other sea lilies, it produces

gamete A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce ...

s in specialised areas of the pinnules and releases them into the sea. After fertilisation, the

eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

hatch into barrel-shaped doliolaria

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e. These have several bands of cilia which enable them to swim. The larvae are

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...

ic and after a few days settle on the seabed and undergo metamorphosis into juvenile sea lilies.

References

{{Taxonbar, from=Q18606503 Isselicrinidae Crinoid genera Monotypic echinoderm genera Animals described in 1885