Pycnopodia helianthoides (Brandt, 1835)

Common name(s): Sunflower star, Many-legged sunflower, Twenty-rayed star

Synonyms:
Phylum Echinodermata
 Class Asteroidea
  Order Forcipulatida
   Suborder Asteriadina
    Family Asteriidae
Pycnopodia helianthoides captured subtidally from Sares Head.
(Photo by: Dave Cowles, July 2000)
Description:  This is the largest seastar in the Rosario area, with a diameter of up to 90 cm.  It has 20 or more rays (but occasionally may be as few as 15), abundant pedecellariae, and many spines projecting from its limp, flaccid tissue (picture).  A row of spines along the margins of the rays is longer than the other spines.  Nearly always orange or pinkish; sometimes purplish (photo), yellowish, or brown; with white spines.

How to Distinguish from Similar Species: This seastar is larger and has more rays than any other seastar in our area.  Small individuals could be confused with Solaster dawsoni or Crossaster papposus, but both of those species have 16 or less rays, have no pedicellariae, and are not as markedly limp as Pycnopodia is..  S. dawsoni also does not have the prominent projecting spines, and C. papposus' spines are not extra prominent along the margins of the rays as they are in this species.

Geographical Range: Unalaska Island, Alaska to Baja California; uncommon south of Monterey Bay

Depth Range: Low intertidal to 435 m.  Nearly always subtidal.

Habitat: Mostly subtidal, rocky, gravelly, or sandy bottoms.

Biology/Natural History: This species is a voracious subtidal predator, feeding on bivalves, snails, chitons, urchins, other asteroids, sea cucumbers, sand dollars, and crabs (in other words, just about anything it wants!).  It will also scavenge dead animals.  It may be the largest and fastest seastar in the world.  It can move up to 3 meters per minute, and has been known to travel at least 3 km.  It has over 15,000 tube feet.  Tiny, newly metamorphosed juveniles of this species have only 5 rays but rays are added as the individual grows.  Has very prominent spines and (crossed) pedicellariae, plus purple papulae.  Loss of rays upon handling seems to be due to autotomy.  In Puget Sound this species excavates butter clams (Saxidomus gigantea) by picking up sediment particles over the clam, passing them out to the ends of the rays, and dropping them.  Often eat urchins such as Strongylocentrotus purpuratus, whose spines may pierce through from the stomach to the aboral surface.  Can evert its stomach but more often swallows its prey whole.  Predators include Alaska King crab and some large Cancer crabs.  Individuals are agressive toward one another (and to almost any other seastar).  Spawns March to July (some also in winter); has fertilizable eggs at least from December to June.  May stand on the tips of their rays while spawning.  Pelagic larvae metamorphose to benthic, 5-rayed juveniles at 9-10 weeks.

This species has a large, fleshy body with an only loosely articulated skeleton, and relies on fluid pressure to maintain its body form.  It appears to rely more heavily on fluid uptake through the surface than on uptake through the madreporite.  Its perivisceral fluid is more hyperosmotic than that of several other local species.  This may aid in fluid uptake (Ferguson, 1994) and maintaining body form.



 
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References:

Dichotomous Keys:
Flora and Fairbanks, 1966
Kozloff 1987, 1996
Smith and Carlton, 1975

General References:
Gotshall and Laurent, 1979
Harbo, 1999
Kozloff, 1993
Morris et al., 1980
Niesen, 1997
O'Clair and O'Clair, 1998

Scientific Articles:

Brewer, Reid and Konar, Brenda, 2005.  Chemosensory responses and foraging behavior of the seastar Pycnopodia helianthoides.  Marine Biology 147(3): pp 789-795 (abstract):  (Pycnopodia bypassed uninjured prey of the butter clam Saxidomus giganteus in favor of injured individuals; apparently due to chemical cues.)

Ferguson, John C., 1994.  Madreporite inflow of seawater to maintain body fluids in five species of starfish.  pp. 285-289 in Bruno David, Alain Guille, Jean-Pierre Feral, and Michel Roux (eds).  Echinoderms through time.  Balkema, Rotterdam.

Greer, D., 1961.  Feeding behavior and morphology of the digestive system of the seastar Pycnopodia helianthoides.  M.S. Thesis, University of Washington, Seattle, WA

Mauzey, K.P., C. Birkeland, and P.K. Dayton, 1968.  Feeding behavior of asteroids and escape responses of their prey in the Puget Sound region.  Ecology 49: pp 603-619

Mladenova, P., S. Igdoura, S. Asotra, and R. Burke, 1989.  Purification and partial characterization of an autotomy-promoting factor from the sea star Pycnopodia helianthoides.  Biological Bulletin 176:  pp. 169-175

Moitoza, D. and D. Phillips, 1979.  Prey defense, predator preference, and nonrandom diet:  The interactions between Pyconopdia helianthoides and two species of urchins.  Marine Biology 53:  pp 299-304

Nishizaki, Michael T. and Josef Daniel Ackerman, 2005.  A secondary chemical cue facilitates juvenile-adult postsettlement associations in red sea urchins.  Limnology and Oceanography 50(1): pp 354-362 (Adult Strongylocentrotus franciscanus urchins release a chemical signal which causes young urchins to aggregate underneath them when the adults detect the presence of Pycnopodia helianthoides)
 



General Notes and Observations:  Locations, abundances, unusual behaviors:

This is a common species subtidally in the area around Rosario.



The animal is so flaccid that if its body is held long in the air, rays will break off and fall, as has happened to this specimen just above my hand.  Photo by Dave Cowles, July 1997


Besides the large spines and pedicellariae on the aboral side, this seastar has long tube feet on the oral side.  Note that this individual has been recently feeding, as indicated by the partly everted stomach.
Photo by Dave Cowles at San Simeon, CA, April 1997

This seastar can move extremely rapidly for a seastar.  Its presence elicits an escape reaction from many species such as the spiny scallop Chlamys hastata (click here for an .MPG movie), the sea cucumber Parastichopus californicus, and limpets.  This movie shows how fast the animal is able to move its long tube feet.


June 2005:  Brought in an individual from outer Rosario Bay that was 76 cm in diameter.  Held by Dave Cowles and Greg Ryals.



This species is usually found subtidally but can sometimes be found in the very low intertidal or in cave tidepools, as this one was.
Note the purple color.

Baby

This tiny individual was in the intertidal at Cape Flattery, WA.  Photo by Dave Cowles, July 2010.



Authors and Editors of Page:
Dave Cowles (2005):  Created original page