Stylasterias forreri
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Stylasterias forreri |
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| ( de Loriol , 1887) |
Stylasterias forreri is a species of starfish from the order of the pincer stars (Forcipulata), which is found on the Pacific coast of Canada and the United States . The starfish, which can be up to one meter in size, prey on bottom-living fishwith its pedicellariums .
features
Stylasterias forreri can reach a diameter of 1 m, but is usually significantly smaller. The central disc is comparatively small, the 5 (occasionally 6) arms long and tapering to a point. 3 to 5 rows of 4 mm to 5 mm white spines run along the top of the arms, each surrounded by a ring of 30 to 40 pedicellariums . Tufts of pale skin gills sit between the spines. When the starfish is touched, the pedicellariums cling like a Velcro fastener and are difficult to remove. The starfish is gray to black, occasionally beige.
Distribution and occurrence
Stylasterias forreri lives on the Pacific coast of the United States and Canada on both rocky and sandy subsoil below the intertidal zone to a depth of about 540 m.
nutrition
With its pedicellariums, Stylasterias forreri prey on agile animals such as decapods ( sand crabs : Emerita analoga ) and small bottom-living fish . If a person touches the starfish with his hand, the impression of a strong Velcro fastener is created (hence the English name velcro star "Klettstern"). The pedicellariums are stretched when the water moves and snap shut 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.
Predators
An important predator of Stylasterias forreri is the solar star Solaster dawsoni . He defends himself against this by wrapping his arms around the attacker and pinching with the pedicellarians. In this way the sun star is often put to flight.
Confusion with Astrometis sertulifera
Stylasterias forreri , originally described under the name Asterias forreri , is sometimes confused with the similar fish-catching Astrometis sertulifera . While this is found in the intertidal zone, Stylasterias forreri only occurs below 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 largely resembles the starfish described by Jennings in terms of prey capture behavior (but not in a number of other characteristics).
literature
- Philip Lambert: Sea Stars of British Columbia, Southeast Alaska, and Puget Sound . Royal British Columbia Museum, University of British Columbia Press, Vancouver 2000. Stylasterias forreri , pp. 143-146.
- GA Robilliard (1971): Feeding behavior and prey capture in an asteroid Stylasterias forreri . Syesis 4, pp. 191-195.
- Fu-Shiang Chia, Helen Amerongen. On the prey-catching pedicellariae of a starfish, Stylasterias forreri (de Loriol) . Canadian Journal of Zoology, 1975, 53 (6).
- Walter Kenrick Fisher: Asteroidea of the North Pacific and Adjacent Waters: Phanerozonia and Spinulosa . United States National Museum, US Government Printing Office, 1928. p. 96. Genus Stylasterias, emended . P. 96ff. Stylasterias forreri (de Loriol) .
- HS Jennings (1907): Behavior of the starfish, Asterias forreri de Loriol . University of California Publications in Zoology 4 (2), pp. 53-185.
Web links
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.