Pisaster brevispinus
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Pisaster brevispinus |
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| Scientific name | ||||||||||||
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| Stimpson , 1857 |
Pisaster brevispinus is a species of starfish from the order of the pincer stars (Forcipulata), whichis nativeto the North American Pacific coast .
features
Pisaster brevispinus can reach a diameter of about 60 cm and a body mass of up to 1 kg. The spines on its top are less than 2 mm long. His body is soft and pliable. His stomach can be everted about 8 cm.
Reproductive cycle
Like other starfish, Pisaster brevispinus is segregated. Females and males come together in groups and at the same time release their germ cells into the open sea, where the egg cells are fertilized by the sperm. Bipinnaria larvae, living as plankton, emerge on the inseminated eggs and feed on phytoplankton . In the next stage of Brachiolaria , the larvae form a primordium, attach themselves to a solid substrate and metamorphose into a small starfish, which takes them about 2 days.
Distribution and occurrence
Pisaster brevispinus is along the North American Pacific coast of Sitka ( Alaska ) to Santa Barbara in California frequently. Since it does not tolerate drought, it lives below the intertidal zone to depths of 180 m and is only occasionally seen above water at very low water levels. Here it can be found on sandy and muddy ground, younger specimens also on rocks and stakes.
nutrition
Pisaster brevispinus feeds on sea urchins ( sand dollars : Dendraster excentricus ) and mussels ( Saxidomus , Protothaca ), which it digs out of the sandy substrate. To do this, he can extend the suction feet next to his mouth about 20 cm into the sediment. It also eats tube worms and other animals living on solid substrates such as mussels ( Mytilus californianus ), oysters ( Crassostrea gigas ) and barnacles ( Balanus , Tetraclita , Mitella ). Syringe worms of the genus Phascolosoma , cockles ( Cardium ), trough clams ( Tresus ) and pygmy olive snails ( Olivella biplicata ) were also observed as prey . As a scavenger, it also feeds on dead fish and cephalopods .
literature
- Howard M. Feder: Asteroidea , in: Robert Hugh Morris, Donald Putnam Abbott, Eugene Clinton Haderlie: Intertidal Invertebrates of California . Pp. 117–135, here p. 127, 8.15: Pisaster brevispinus (Stimpson, 1857) . Stanford University Press, 1st ed., Stanford (CA, USA) 1980.
- Lynwood S. Smith (1961): Clam-digging behavior in the starfish Pisaster brevispinus (Stimpson, 1857) . Behavior 18, pp. 148-153.
- J. Nybakken: Diversity of the invertebrates . California State University, Hayward 1996.
Web links
- T. Hiebert, K. Meyer (2015): Pisaster brevispinus
- Pisaster brevispinus (Stimpson, 1857) . Rosario Beach Marine Laboratory, Walla Walla University.