Pteraster tesselatus Ives, 1888

Common name(s): Slime star, Cushion star

Synonyms: Animal
Phylum Echinodermata
 Class Asteroidea
  Order Spinulosida
   Suborder Eugnathina
    Family Pterasteridae
Pteraster tesselatus from 10 m depth, Sares Head.
(Photo by: Dave Cowles, July 1997)
Description:  This 5-rayed seastar has a thick, broad central disk and rays approximately as long as the central disk is wide.  It has no conspicuous marginal plates; in fact, the entire aboral surface is covered with a thick, loose, elevated fleshy membrane, giving it a fairly smooth texture and soft feel.  The madreporite cannot be seen--instead, a central pore opens into the spongy space between the membrane and the aboral surface.  When disturbed, often secretes large amounts of a thick, viscous slime.  Color yellowish brown or pale orange.  Diameter about 15 cm.

How to Distinguish from Similar Species: No other common local species secretes the copious slime nor has the elevated membrane over the aboral surface.  Dermasterias imbricata is not as thick, the madreporite can be seen, and is usually reddish brown with gray or purple.  Asterina miniata and Mediaster aequalis have obvious plates (ossicles) on the aboral surface.

Geographical Range: Bering Sea to Carmel Bay, CA

Depth Range: 5 to 950 m

Habitat: Rocky areas

Biology/Natural History: Diet includes sponges such as Halochondria panicea, Aplidium, Didemnum, and Corella inflata tunicates, and bivalves such as the falsejingle Pododesmus macroschisma.  Ambulacral grooves may have the symbiotic polychaete worm Arctonoe pulchra,  A. vittata, or Ophiodromus pugettensis.

Return to:
Main Page Alphabetic Index Systematic Index Glossary


Dichotomous Keys:
Kozloff 1987, 1996

General References:
Gotshall and Laurent, 1979
Morris et al., 1980
O'Clair and O'Clair, 1998

Scientific Articles:

Emlet, Richard B., 1994. Body forms and patterns of ciliation in nonfeeding larvae of echinoderms: functional solutions to swimming in the plankton? American Zoologist 34: pp. 570-585

Knott, K. Emily, and Gregory A. Wray, 2000. Controversy and consensus in Asteroid systematics: new insights to Ordinal and Familial relationships. American Zoologist 40:3 pp. 382-392

Levina EV, Andriyaschenko PV, Kalinovsky AI, Stonik VA., 1998.  New ophiuroid-type steroids from the starfish Pteraster tesselatus.  J Nat Prod. 61(11):1423-6. (PubMed)

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: 603-619

McEdward, L.R., 1992.  Morphology and Development of a Unique Type of Pelagic Larva in the Starfish Pteraster tesselatus (Echinodermata: Asteroidea).  Biological Bulletin 182(2) 177-187 (Abstract)

McEdward, Larry R. and Benjamin G. Miner, 2006.  Estimation and interpretation of egg provisioning in marine invertebrates.  Integrative and Comparative Biology 46:3 pp 224-232

Rodenhouse, I.Z. and J.E. Guberlet, 1946.  The morphology and behavior of the cushion star, Pteraster tesselatus (Ives).  University of Washington Publications in Biology 12: 23-47

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

Underside of Pteraster tesselatus.  Ray length of this individual is 8 cm.  Photo by Dave Cowles June 2006.

A closeup view of the tube feet along one ambulacrum.  Photo by Dave Cowles, June 2006

Another individual from subtidal Sares Head.  Note the flabby-looking aboral side, caused by the extra membrane above the actual aboral side.  This individual will
be in danger of dying when placed back into seawater if any bubbles have gotten into the space between the outer membrane and the aboral surface, because it will
cause the animal to float around the tank uncontrollably.  This species is best left submerged at all times.  Photo by Dave Cowles, July 2000.

In this photo, taken underwater off Northwest Island by Kirt Onthank (Feb 2006), Pteraser tesselatus is seen near hydroids and the sea cucumber Psolus chitonoides.

This colorful individual from Sares Head has a span of about 15 cm.

This closeup of the end of a ray (aboral view) shows how the tube feet at the ray tips are extended when the animal is actively moving
Closed Partially open Fully open and exhaling.  Water flow is great enough to cause a distortion of the water surface 2 cm above opening.
This species exhales a stream of water through its dorsal opening every few minutes.  This series of photos shows the dorsal opening closed (as it appears just after an exhalation), then partially open as it often appears, and finally in the fully open, exhaling condition.  The full flow of the exhalation takes around 5 seconds.   Click Here to view a movie of the full inhalation-exhalation cycle.

The Vancouver Aquarium ( states that this species is circumpolar; however, their photos do not look like this species.  Our local species may be the subspecies arcuatus.

An underwater photo by Kirt Onthank, June 2007

Occasionally individuals with 6 rays instead of 5, such as the 12-cm diameter individual, are found.  Photo by Dave Cowles, July 2013.

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