Ophiocoma echinata (Lamarck 1816)

Ophiocoma echinata is eaten by some fish.

The brittle star owes its name to the particular habit of voluntarily breaking off arms and portions of the central disk. There are no reproductive or digestive organs located in the arms, and loss is relatively inconsequential. An arm boken at the central disk can regenerate completely in 10 months. Another interesting fact about the star is the changing of colors from day to night. The adults are much paler at night than during the day.

US Federal List: no special status

CITES: no special status

Development - Life Cycle: metamorphosis

The spiny brittle star has no negative economic effects on humans.

Brittle stars have in the past only affected humans by figuring into the diets of commercially important marine life such as crabs, shrimp, and fish. Recently scientists have been researching the symbiotic relationship with a bacteria that lives between the stars' protective cuticle and inner skin layer. These bacteria protect the star from infection when arms are broken off. This research has great potential for antibiotic drugs and treatment of human diseases.

The spiny brittle star is primarily a deposit and filter feeder, although some of the stars have been reported as carnivorous. The arms of the stars move from side to side, curving upward to intercept detritus and plankton. The food particles are caught in mucous strands strung between the spines and are then moved down to the mouth by the podia. Larger material is swept to the mouth by a looping action of the lateral movement of the arms. The stars feed mainly on pieces of fleshy algae, but some have been known to feed on eggs from damselfish nesting sites. The species possess an incomplete digestive tract, with the mouth also functioning as the anus, which is very unusual for an echnioderm. Feeding is done predominantly at night when the risk of predation is greatly reduced.

Animal Foods: fish; eggs

Plant Foods: algae

Other Foods: detritus

Foraging Behavior: filter-feeding

Primary Diet: carnivore (Piscivore , Eats eggs); omnivore ; planktivore ; detritivore

The spiny brittle star can be found along the eastern coastlines of Central and South America to Brazil, Florida, and the majority of the islands in the Caribbean Sea.

Biogeographic Regions: atlantic ocean (Native )

Spiny brittle stars occupy reefs and reef flats, particularly those abundant in rubble. The stars are also found in seagrass beds and mangroves, under rocks, and in old coral heads. They live in shallow intertidal waters with depths up to 24 meters.

Elevated water temperatures at low tides can kill some individuals.

Range depth: 24 (high) m.

Habitat Regions: saltwater or marine

Aquatic Biomes: reef ; coastal

One of the larger brittle stars, Ophiocoma echinata can measure up to 32 mm in disk diameter and 150 mm in arm length. The spiny brittle star shares the characteristic body plan of echinoderms, with 5 arms that are well defined from the central disk. The aboral, or top, side of the star is dark brown and sometimes mottled with lighter hues. The arms are usually banded in shades of brown and the oral, or bottom, surface is white in color. The central disk is granular and exhibits a scalloped border. The mouth is located on the oral surface and consists of 5 triangular jaws, each with a central column of teeth. The arms extend out from the muscular jaws and are covered by 4 rows of shields, or calcareous plates. Each arm joint has a vertical row of 4 spines on either side. The length of the spines decease towards the tip of the arm and the spine closest to the mouth is club-shaped. Unlike the asteroids (sea stars), brittle stars have no umbulacral groove and lack the suction apparatus on the podia of the oral surface on the arms.

Range length: 150 (high) mm.

Other Physical Features: ectothermic ; heterothermic ; radial symmetry

Spiny brittle stars have testes and ovaries consisting of clusters of gametes in sac-like cavities called bursae. An individual 22 mm in disk length can contain 888,000 eggs. Sexes are separate, however, no sex differences have evolved because no sex recognition is necessary in the spawning process. Fertilization is external. Spawning takes place at night when the predation pressure is lowered. The stars assume a pop-up postion with the central disk lifted above the substratum and release a stream of gametes, either oocytes or spermatozoa, from the bursal slits. The male and female gametes must meet midstream to form a zygote. The fertilized eggs develop into larvae and are moved by the ocean current. After a few weeks, metamorphosis is complete and the larvae become juvenile spiny brittle stars.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous

Parental Investment: no parental involvement

In Panama this species has been collected in the Caribbean from Galeta Island (USNM E 24060), Margarita Island (USNM E 26511), Fort Sherman (USNM E 24059), Del Parde Island (USNM E 51820), and in San Blas from Miria Island (USNM E 24069) and Pico Feo Island (USNM E 24115).

Clark, H.L. (1921). The echinoderm fauna of Torres Strait: its composition and its origin. Department of Marine Biology of the Carnegie Institute 10: 1-218.

Lamarck, J.B. de. (1816). Ordre Second. Radiaires Échinodermes. Histoire naturelle des animaux sans vertèbres, 2, 522-568.

Say, T. (1825). On the species of the Linnaean genus Asterias inhabiting the coast of the U.S. Journal of the Academy of natural sciences of Philadelphia, 5, 141-154.

Pawson, D. L., D. J. Vance, C. G. Messing, F. A. Solis-Marin, and C. L. Mah. (2009). Echinodermata of the Gulf of Mexico, Pp. 1177–1204 in Felder, D.L. and D.K. Camp (eds.), Gulf of Mexico–Origins, Waters, and Biota. Biodiversity. Texas A&M Press, College S.

GenBank

World Ophiuroidea Database

LSID urn:lsid:marinespecies.org:taxname:243573

Ophiocoma crassispina (Say, 1825) (synonym)
Ophiocoma tumida Müller & Troschel, 1842 (synonym)
Ophiura crassispina Say, 1825 (synonym)
Ophiura echinata Lamarck, 1816

Ophiocoma echinata, common name black brittle star, is one of the larger species of brittle stars.

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 and is found in the tropical west Atlantic Ocean, the Caribbean Sea and the Gulf of Mexico.

Disk circular to pentagonal (dd = 3.06 to 16.68 mm). Uniformly covered by small granules (Fig. 11a), which are smaller in central region than in marginal region. These granules occupy a v-shaped area on the ventral interradius (Fig. 11b). In the areas without granules there are large and imbricating scales. Bursal slits enlarged, with well developed genital scales in margins (Fig. 11b). Oral shields large and rectangular, proximal margin slightly rounded (Fig. 11c). Adoral shields small, almost totally covered by oral shield. Four oral papillae on each side of jaw angle (Fig. 11c). Two proximal papillae slightly cylindrical and subequal, two distal papillae longer and broader. Cluster of well developed dental papillae on apex of jaw (Fig. 11c). Dorsal arm plate longer than wide, fan-shaped (Fig. 11d). Ventral arm plate longer than wide, octogonal, with distal margin slightly convex (Fig. 11e). Two tentacle scales, internal one slightly larger than external one. Three or four arm spines alternating on arm segments. Dorsal spine longer and broader (bottle-shaped) (Fig. 11d), median ones of equal size and ventral one smaller and slightly flattened.

Bermuda, Florida and the islands off southern Florida, the Bahamas, the Antilles, the Mexican Caribbean, Belize, Nicaragua, Guatemala, Honduras, Costa Rica, Panama, Colombia, Venezuela, and Brazil (Lyman 1865, H.L. Clark 1933, Hendler et al. 1995, Durán-Gonzáles et al. 2005, Alvarado et al. 2008). In Brazil from Ceará (Albuquerque 1986), Paraíba (Rathbun 1879), Pernambuco (Tommasi 1970), Alagoas (Miranda et al. 2012), Bahia (Tommasi 1970), and Rio de Janeiro (Manso 1993). Intertidal to 24m. Recorded herein between 10 and 34m.