''Ophiocoma echinata'', the spiny ophiocoma, is a species of
brittle star belonging to the
family Ophiocomidae. It is the
type species of the genus ''
Ophiocoma
''Ophiocoma'' is a genus of brittle stars belonging to the family Ophiocomidae.
Selected species
* ''Ophiocoma aethiops'' (Lütken, 1859)
* ''Ophiocoma echinata'' (Lamarck, 1816)
* ''Ophiocoma erinaceus'' (Müller & Troschel, 1842)
* ''Ophiocoma ...
'' and is found in the tropical west Atlantic Ocean, the Caribbean Sea and the Gulf of Mexico.
Description
''Ophiocoma echinata'' is a large brittle star, with a maximum armspan of . The slender, tapering arms are densely clad with short spines and are clearly demarcated from the disc. The colour is dark with pale or cream-coloured markings, but the arms never have any red markings.
Distribution and habitat
''Ophiocoma echinata'' is native to the tropical west Atlantic Ocean, the Caribbean Sea and the Gulf of Mexico. It is common throughout the Caribbean at depths down to about . It occurs in
seagrass meadow
A seagrass meadow or seagrass bed is an underwater ecosystem formed by seagrasses. Seagrasses are marine (saltwater) plants found in shallow coastal waters and in the brackish waters of estuaries. Seagrasses are flowering plants with stems and ...
s, on reefs and reef flats, hiding under rocks, in cracks and crevices, under
coral heads,
[ and inside sponges.][
]
Behaviour
''Ophiocoma echinata'' uses its arms to burrow in the sand and anchor itself in crevices. It holds some of its arms vertically in the passing water current to filter food particles, catching them with the spines and passing them along feeding channels to the mouth. The stomach is entirely within the central disc and is the organ of food storage.substrate
Substrate may refer to:
Physical layers
*Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached
** Substrate (locomotion), the surface over which an organism lo ...
while the tube feet on the arms grip the surface.[ Despite having no brain and only having a simple, ring-shaped nervous system, ''O. echinata'' is able to adopt a coordinated pattern of locomotion in which one arm leads the way and the others act in synchrony to propel it forward. When the brittle star alters its direction of travel, it does not rotate, but instead a different arm becomes the lead arm and the other arms take on the subordinate role. This shows that a radially symmetrical animal can employ fully coordinated, bilaterally symmetrical locomotion.
When attacked by a predator, ''O. echinata'' sometimes autotomises (sheds) one or more of its arms. In a back-reef habitat in the ]Florida Keys
The Florida Keys are a coral cay archipelago located off the southern coast of Florida, forming the southernmost part of the continental United States. They begin at the southeastern coast of the Florida peninsula, about south of Miami, and e ...
, up to 47% of the individuals were found to have missing or damaged arms, and it took about two years for individuals with three missing arms to completely regenerate them. Losing a limb rather than its life is beneficial to the brittle star. Although energy must be diverted to effect the repair and regrowth, the individual should still be able to breed at some time in the future, and the missing arm contributes a renewable resource to the productivity
Productivity is the efficiency of production of goods or services expressed by some measure. Measurements of productivity are often expressed as a ratio of an aggregate output to a single input or an aggregate input used in a production proces ...
of the reef.
References
{{Taxonbar, from=Q2229216
Ophiocomidae
Animals described in 1816