Starfish (redirected from starfishes)

starfish: see sea star.

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starfish

 or sea star

Principal features of a starfish. Water for the water vascular system enters through the …

(credit: © Merriam-Webster Inc.)

Any of 1,800 echinoderm species (class Asteroidea) that have regenerable arms surrounding an indistinct disk and that inhabit all oceans. Species range from 0.4 to 25 in. (1–65 cm) across, but most are 8–12 in. (20–30 cm) across. Their arms, usually five, are hollow and, like the disk, covered with short spines and pincerlike organs; on the lower side are tube feet, sometimes sucker-tipped, used for creeping or clinging to steep surfaces. Some species sweep organic particles into the mouth on the underside of the disk. Others either evert the stomach upon their prey for external digestion or swallow the prey whole.

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starfish

any echinoderm of the class Asteroidea, such as Asterias rubens, typically having a flattened body covered with a flexible test and five arms radiating from a central disc

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starfish [′stär‚fish]

(invertebrate zoology)

The common name for echinoderms belonging to the subclass Asteroidea.

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Starfish 

any one invertebrate of the class Asteroidea of the phylum Echinodermata. The body is in the form of a five-rayed (sometimes poly act, with up to 50 rays) star or pentagon. It measures from 1 cm to 1 m. Many starfish are brightly colored. The skeletal plates of the skin are armed with spines, needles, and sometimes pedicellariae. These bottom-dwelling animals crawl by means of numerous ambulacral feet. The majority of starfish are predators, feeding mainly on mollusks and other invertebrates. Some evert their stomachs, enveloping their prey and digesting it outside the body. Starfish are predominantly dioecious. They usually develop from free-swimming larvae (bipinnarias, brachiolariae), which undergo metamorphosis. Some starfish are viviparous. The ability to regenerate is highly developed.

There are more than 1,500 species of starfish, distributed in oceans and seas throughout the world (except waters of low salinity) to depths of 8.5 km. More than 150 species are found in the seas of the USSR. Some starfish are destructive in that they prey on commercially valuable mollusks (oysters, mussels), others, such as Acanthaster planci, feed on reef-forming corals. Starfish are known in fossil form from the Ordovician.

REFERENCES

Zhizn’ zhivotnykh, vol. 2. Moscow, 1968.
Hyman, L. H. The Invertebrates, vol. 4. New York-London, 1955.