Astrometis sertulifera
| Astrometis sertulifera | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name of the genus | ||||||||||||
| Astrometis | ||||||||||||
| Fisher , 1923 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Astrometis sertulifera | ||||||||||||
| ( Xantus , 1860) |
Astrometis sertulifera is a species of starfish from the order of the pincer stars (Forcipulata) that is found on the Pacific coast of the United States . With its pedicellariums , thestarfishalso prey on agile animals such as crabs and bottom-living fish.
features
Astrometis sertulifera has 5 regular arms that reach arm lengths of about 8 cm. The center disk is small compared to the arms. The top of the arms is covered with clearly delimited, pointed spines, each of which is surrounded at the base by cushions with parrot's bill-like pedicellariums , while tufts of skin gills sit between the spines. When the starfish is touched, the pedicellariums cling like a Velcro fastener and are difficult to remove. The top of the starfish is brown to greenish, the spines purple, orange or blue with red tips, the underside orange.
Distribution and occurrence
Astrometis sertulifera lives on the Pacific coast of the United States from Santa Barbara to the Gulf of California on both rocky and sandy subsoil from the lower tidal zone to a depth of about 40 m.
nutrition
Astrometis sertulifera prey on agile animals with its pedicellariums such as decapods ( sand crabs , including Emerita analoga ) and fish up to the size of the starfish itself. The cushions with the pedicellariums are raised in the event of disturbances, and the pincers of the pedicellarians snap when touched. The victim is then grasped with the suction feet of the neighboring arms, passed on to the mouth opening by movements of the arms and suction feet and swallowed. Other prey are beetles worm , snails , clams , barnacles , brittle stars ( Ophiothrix spiculata ) and sea urchins .
Predators
The predators of Astrometis sertulifera include sun stars of the genus Heliaster . To save itself, the starfish can autotomy an arm and regenerate in the weeks that follow.
Confusion with Stylasterias forreri
Astrometis sertulifera is sometimes confused with the similar, also fish-catching Stylasterias forreri (originally described as Asterias forreri ). While this can only be found below the intertidal zone, Astrometis sertulifera also occurs in it. According to the judgment of Walter Kenrick Fisher (1928), HS Jennings did not describe ( Styl ) Asterias forreri in 1907 , but Astrometis sertulifera . Investigations by GA Robilliard (1971) show, however, that Stylasterias forreri in its prey catching behavior (but not in a number of other characteristics) is largely similar to the starfish described by Jennings, which was probably Astrometis sertulifera .
literature
- Howard M. Feder: Asteroidea , in: Robert Hugh Morris, Donald Putnam Abbott, Eugene Clinton Haderlie: Intertidal Invertebrates of California . Pp. 117–135, here pp. 122f., 8.8: Astrometis sertulifera (Xantus, 1860) . Stanford University Press, 1st ed., Stanford (CA, USA) 1980.
- Walter Kenrick Fisher: Asteroidea of the North Pacific and Adjacent Waters: Phanerozonia and Spinulosa. United States National Museum, US Government Printing Office, 1928. pp. 118f. Genus Astrometis Fisher . P. 119ff. Astrometis sertulifera (Xantus) .
- GA Robilliard (1971): Feeding behavior and prey capture in an asteroid Stylasterias forreri . Syesis 4, pp. 191-195.
- TR Turk (1978): The ecological role of the predatory seastar Astrometis sertulifera in a San Diego rocky intertidal community . PhD dissertation, Ecology, University of California, Riverside, and San Diego State University.
- HS Jennings (1907): Behavior of the starfish, Asterias forreri de Loriol . University of California Publications in Zoology 4 (2), pp. 53-185.
Individual evidence
- ^ Walter Kenrick Fisher: Asteroidea of the North Pacific and Adjacent Waters: Phanerozonia and Spinulosa. United States National Museum, US Government Printing Office, 1928. p. 101. Under the literature referring to forreri is usually cited the paper by Jennings on "Behavior of the Starfish Asterias forreri de Loriol". The species used by Professor Jennings is Astrometis sertulifera (Xantus). Stylasterias forreri is a deepwater species in southern California and only one specimen has ever been taken near La Jolla where Jennings's work was done.