Ophiuroidea

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Related to ophiuroid: class Ophiuroidea, Brittle stars

Ophiuroidea

[äf·ə·yə′rȯid·ē·ə]
(invertebrate zoology)
The brittle stars, a subclass of the Asterozoa in which the arms are usually clearly demarcated from the central disk and perform whiplike locomotor movements.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Ophiuroidea

 

(brittle stars), a class of benthic marine animals of the phylum Echinodermata. The body consists of a flat disk, which usually measures about 2 cm across (sometimes up to 10 cm). Five or, less frequently, ten flexible arms extend from the disk. The length of each arm is several times (sometimes 20 to 30 times) greater than that of the disk. In contrast to the arms of starfishes, the arms of brittle stars are sharply marked off from the disk and are jointed, consisting of numerous vertebrae. Most brittle stars have simple, unbranched arms. The disk and the arms are covered with thin calcareous plates.

In most species the sexes are separate. Development is usually by metamorphosis; the free-swimming larva is called an ophiopluteus. Some species are viviparous; others are capable of reproducing by division.

Brittle stars crawl by flexing their arms, or they bury themselves in the bottom. They feed on small animals or detritus. Many tropical species that inhabit shallows are brightly colored. Some species are capable of luminescence. The regeneration of arms is well developed.

Brittle stars are found throughout the world on ocean and sea bottoms (to depths of 8 km). They often form large colonies and serve as food for fishes. Some species live commensally with algae, sponges, corals, and sea urchins. Of the approximately 2,000 species, about 120 are encountered in the seas of the USSR. Fossils of extinct species have been traced to the Ordovician.

G. M. BELIAEV

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Evolution of abbreviated development in the ophiuroid Ophiarachnella gorgonian involves heterochronies and deletions.
The stations where interrupted fishing effort was identified presented a higher biomass of sessile, like sponges or ascidians, and fragile organisms, like little ophiuroids, than the sites continuously disturbed up to 2007.
Furthermore, orthonectid species mainly parasitize only a single host species or, in some uncommon cases, multiple related species (e.g., Rhopalura ophiocomae, being found from Amphipholis squamata, Ophiothrix fragilis, and Ophiura albida, which are all ophiuroids) (Giard, 1877; Fontaine, 1968; Kozloff, 1969, 1992; Bender, 1972).
Interestingly, WE and ME independently have been detected in eggs and planktonic stages of several species, such as abalone (Moran and Manahan, 2003), squid (Steer et al., 2004), fish (Hilton et al., 2008), sea stars (Prowse et al., 2008, 2009), and ophiuroids (Prowse et al., 2009), where they are usually found in trace amounts (see Moran and Manahan 2003 and Prowsc et al., 2009).
Similar morphological patterns were observed for autotomy in the feather star Florometra serratissima (Holland and Grimmer, 1981) and ophiuroids (Wilkie and Emson, 1987; Dobson and Turner, 1989).
and the ophiuroids Ophiacantha sp., Ophiocten sp., and Ophiopleura sp.) were found in more than one geographical region (Table 4).
johanni, and Macoma calcarea; gastropods such as Cylichna alba; polychaetes such as Sternaspia scutata, and Scalibregma sp.; Nephtydae; Terebellidae; amphipods; and ophiuroids. Other Bering Sea studies (Feder, 1977, 1978) also found polychaetes, bivalves, amphipods, and nemerteans to be major food items for Alaska plaice.
Over roughly the same interval, communities with abundant stalked crinoids, ophiuroids, articulate brachiopods, or reclining bivalves disappeared from soft-bottom shelf habitats [ILLUSTRATION FOR FIGURE 2 OMITTED].
Animals were separated into their major groups: annelids, crustaceans, mollusks, nemerteans, ophiuroids, sipunculids, and others and put on aluminum pans.
When the shrimps are in the adult stages and fully grown up they are bottom feeder, i.e., they crawl on the sea floor while catching slow moving creatures like small crustaceans, fin-fish, moluses, polychaetes (worm with bristles), ophiuroids (starfish like) and many other slow moving benthic organisms.
bahamondei was conducted by Andrade & Baez (1980), who reported 13 different components in the stomach contents, including sediment and remains of crustaceans, tanaidaceans (Apseudes), and ophiuroids (Ophiomastus molinae).