Ochre Sea Star (Pisaster ochraceus)

Description: Ochre stars, also known as purple stars, are a beautiful species of sea star that come in a wide array of colors from deep purple to red to various shades of orange. Ochre sea stars generally have 5 arms and can reach sizes of 50 cm in width (arm to arm). This intriguing creature is an echinoderm, which translates to “spiny skin.” Like other echinoderms, it has little white bumps on the topside of its body called ossicles. These ossicles are part of a sea star’s endoskeleton and they provide rigidity and protection. On the underside of a sea star, one will find tons of little tube feet that sea stars use to move, grab prey, and cling onto rocks. The mouth is also located on the underside of this sea star.

Habitat: Ochre sea stars live in the intertidal zone, ranging geographically from Alaska to Baja California, Mexico. Ochre sea stars prefer clinging onto rocks, often underneath mussel beds. To find one, it’s best to get down low and look within rock crevices and underneath rocky overhangs. They sometimes like to cling onto each other in dense groups.

Diet: Ochre sea stars love eating mollusks, especially mussels. To do so, they only have to pry open a mussel shell a tiny bit in order to slip in a bag-like structure called the cardiac stomach. This is one of two stomachs a sea star has, and the cardiac stomach is able to digest food outside of the body. Once it's done, the stomach is slurped back into the sea star’s mouth with the gooey digested mussel. They don’t have many predators but the main ones are sea otters (rarely seen in Oregon) and gulls.

Tide Pool Tidbits:

• Ochre sea stars are the longest-living species of sea star in the Pacific Northwest, reaching ages of up to 20 years old.

• Many of the ochre stars prey species can detect its presence in the water and quickly retreat.

• Sea stars at Haystack Rock often have to survive outside of the water for up to 8 hours at a time during our really low tides. Lab studies have shown these stars may even be able to survive up to 50 hours of exposure!

Reference: Walla Walla University, The New Beachcomber’s Guide to the Pacific Northwest by J. Duane Sept