California sun star

(Rathbunaster californicus)

Don’t be fooled by this star’s sunny disposition.

A California sun star has a voracious appetite and it’s not picky about its next meal. It scuttles along the mud on an army of tiny tube feet, following the scent of a rotting feast. But this sea star doesn’t just dine on scavenged scraps—it can be a cunning predator. It feasts on crabs, amphipods, worms, and other small invertebrates by trapping them in its arms and swallowing a meal whole.

The surface of the star is also covered in tiny spines lined with pincers that puff up like pom-poms. When something swims too close or crawls on top, those pincers grab tight to help capture potential prey. Remarkably, MBARI’s remotely operated vehicles (or ROVs) have even seen this species snag fast-moving prey passing in the currents. A hungry sun star raises an arm to grab krill, shrimp, and fishes from the waters overhead.

Like other sea stars, this sun star can shed its arms when threatened. While the wiggling arm distracts its predator, the star scurries to safety and will regenerate its lost limbs.

Fast Facts

Maximum size: 45 centimeters (18 inches) across

Depth: 60–1,000 meters (200–3,300 feet)

Habitat: muddy seafloor

Range: southern Alaska to southern California

Diet: crustaceans, worms, detritus, and occasionally fishes


Research publications

Edgington, D.R., I. Kerkez, D. Oliver, D.E. Cline, L. Kuhnz, D. Walther, M. Ranzato, and P. Perona (2005). “Detection and classification of Rathbunaster californicus in underwater video.” Paper presented at American Geophysical Union, Spring Meeting 2005.

Lauerman, L.M.L. (1998). Diet and feeding behavior of the deep-water sea star Rathbunaster californicus (Fisher) in the Monterey Submarine Canyon. Bulletin of Marine Science, 63(3): 523-530.

Lundsten, L., K.L. Schlining, K. Frasier, S.B. Johnson, L.A. Kuhnz, J.B.J. Harvey, G. Clague, and R.C. Vrijenhoek (2010). Time-series analysis of six whale-fall communities in Monterey Canyon, California, USA. Deep-Sea Research I, 57: 1573-1584.

Warén, A. and L.M. Lewis (1994) Two new species of eulimid gastropods endoparasitic in asteroids. The Veliger, 37(4): 325-335.


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