Well-Armed Starfish

With rows of tube feet along the underside of each appendage, Ochre Starfish strong-arm their way to survival.

From Alaska down to Santa Barbara, crashing waves along the Pacific coast may be powerful, but they're no match for the Ochre Starfish (Pisaster ochraceus) that paint the rocky shoreline with splashes of yellow, orange, brown and purple. Common finds for tidepoolers, these starfish are armed with rows of suctioning tube feet that allow them to hold fast to a rock, even in times of turbulence.

An Ochre Starfish can also use its tube feet to pry open the shells of its favorite food - mussels. Once it has created a narrow slit between the hinged halves of a mussel, the starfish extends its stomach and inserts it into the unlucky mollusk, secreting a digestive enzyme that leaves the mussel stewing in its attacker's juices. By the end of this slow-motion meal, only the mussel's shell remains.

For a close encounter with an Ochre Starfish, visit the Academy's Touch Tidepool in the Steinhart Aquarium, or take a tidepooling trip to one of the Bay Area's many coastal treasure troves. When you find one of these well-armed beauties, you can protect it by leaving it in place - pulling it from a rock can tear off the tube feet that help it survive.

Brachiolaria larva of Pisaster ochraceus.
Body length 1450 µ = 1.45 mm. Specimen prepared by T.H.J. Gilmour. Oblique side view.
Photo:T.C. Lacalli from the University of Saskatchewan Archives
Congregation of different color forms of the Ochre Stars (Pisaster ochraceus).
Photo: Nancy Sefton, National Marine Sanctuary.
Mature bipinnaria of Pisaster ochraceus, about 24 days old, raised in culture by T.H.J. Gilmour. Ventral view.
Photo:T.C. Lacalli from the University of Saskatchewan Archives