Six Arm Star

Leptasterias aequalis

Six Arm Star

Leptasterias aequalis

Other Common Names
Colorful six-rayed star, broad six-rayed star, delicate six-armed star

Rocky Coast

Other Common Names

Colorful six-rayed star, broad six-rayed star, delicate six-armed star

At the Aquarium

Rocky Coast

Appearance

This star usually has 6 broad arms and can come in a variety of colors, usually mottled, including: olive-green, coral-red, orange, pink, indigo, or gray. It has flattened, mushroom-shaped spines on its upper surface, and many smaller pedicellariae.

Habitat

Intertidal to shallow subtidal, under rocks or algae

Diet

Carnivore and scavenger; eats sea cucumbers, snails, chitons, mussels, barnacles, and dead animals

Life History

This is a brooding species of sea star, and they brood during the winter. The yellow eggs are 0.036 inches in diameter and there are anywhere from 52-1,491 eggs, with larger females typically producing more eggs with larger embryos. She holds her body in an arch with the eggs on her underside near her mouth, and uses her tube feet to clean the brood. She does not eat for the three months that she is brooding her young. Upon hatching, the larvae attach to the mother using temporary arms and a central adhesive disk. They do not feed during this time. They start to take on a familiar 6-armed star shape by day 44. Once they are fully developed juveniles, they crawl off of their mother. These sea stars can grow to 4 inches across.

IUCN Status

Not Evaluated

Ecosystem & Cultural Importance

These sea stars keep their intertidal environments balanced by feeding on black turban snails. When six arm stars are removed from rocky tidepools, the number of these snails increases, and this allows certain unpalatable algal species to increase their density. When the six arm stars are present, the snails seek out other habitats, and palatable algae species are able to grow.

British Columbia, Canada to California

You might find one of these intertidal inhabitants while tidepooling.

This sea star is known for clinging very tightly to rocks.

Citations & Other Resources

Matt Knoth, Leptasterias hexactis, CC BY 2.0
Invertebrates of the Salish Sea
Jaeckle, William B., Brian L. Bingham, and Kehualani Giles. inchesVariability in broods of the seastar Leptasterias aequalis.inches Canadian Journal of Zoology (2004): 457.
Jaffe, Noah, et al. inchesSea star wasting disease demography and etiology in the brooding sea star Leptasterias spp.inches PLoS One 14.11 (2019): e0225248.
San Francisco State University news article and accompanying video.
Sea Stars of the Pacific Northwest

Six Arm Star

Six Arm Star

Other Common Names

At the Aquarium

Appearance

Habitat

Diet

Life History

IUCN Status

Ecosystem & Cultural Importance

Citations & Other Resources

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