False ochre

Evasterias troschelii

False ochre

Evasterias troschelii

Other Common Names
Mottled star; Troschell’s true star

Rocky Coast

Other Common Names

Mottled star; Troschell’s true star

At the Aquarium

Rocky Coast

Appearance

Named for its resemblance to the ochre star; it has a relatively smaller central disc relative to its 5 tapering arms that can reach 11.8 inches long. In addition, spines on the central disc of the ochre star make a star pattern, a feature that is absent on the false ochre star. This sea star comes in a variety of uniform or mottled colors, including drab greens, browns, and greys, or bright orange. It has larger blunt white spines and smaller, sharper white spines.

Habitat

Intertidal to subtidal depths of 250 feet, in eelgrass, on rock, boulders, cobble/sand, and on docks and pilings.

Diet

Primarily eats mussels and barnacles, but also eats limpets, snails, chitons, worms, and tunicates

Life History

False ochres reproduce by broadcast spawning. The larvae start life as plankton, spending several months feeding in the water column. They then undergo metamorphosis into the juvenile form and settle onto the bottom.
Can grow up to 31 inches across.

IUCN Status

Not Evaluated

Ecosystem & Cultural Importance

Will sometimes provide a home to a scaleworm; Alaskan king crabs will sometimes hang out in its arms.
As prey they feed gulls, various sea stars, Alaskan king crabs, and sea otters, who might feed on them when their gonads are ripe.

Alaska to California

These sea stars may be encountered while tidepooling.

Gulls are able to eat false ochre stars until their arms reach a length of 4.7 inches. While young and small, these sea stars live in boulder habitats, which are structurally complex and provide hiding spaces. Once they grow larger and less susceptible to predation, they will move into more open habitats such as rocky shores and pilings, where food is more abundant.

This animal is able to detect prey through scent. It will envelope the prey with its arms, hunch over, and use its tube feet to force open shellfish. It can take about 20 minutes for a false ochre to open a mussel. To eat, it everts its stomach out through its mouth, stretching as far as half the length of one of its arms, and digests the soft tissue of its prey.

Citations & Other Resources

Christensen, Aage Møller. inchesThe feeding behavior of the seastar Evasterias troschelii Stimpson.inches Limnology and Oceanography 2.3 (1957): 180-197.
Invertebrates of the Salish Sea
Jewett, Stephen C., et al. inchesField guide to sea stars of the Aleutian Islands.inches (2015).
Rogers, Tanya L., and Joel K. Elliott. inchesDifferences in relative abundance and size structure of the sea stars Pisaster ochraceus and Evasterias troschelii among habitat types in Puget Sound, Washington, USA.inches Marine Biology 160 (2013): 853-865.
Sea Stars of the Pacific Northwest website
SIMoN (Sanctuary Integrated Monitoring Network) website

False ochre

False ochre

Other Common Names

At the Aquarium

Appearance

Habitat

Diet

Life History

IUCN Status

Ecosystem & Cultural Importance

Citations & Other Resources

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