Sunflower Stars

Pycnopodia helianthoides

Sunflower Stars

Pycnopodia helianthoides

At the Aquarium

Rocky Coast

Appearance

Large and soft star with 15-24 arms that can reach lengths of 23.6 inches each. Variable colors include beige, orange, red, gray or purple.

Habitat

Habitat generalist: mud, sand, shell, rocky bottoms, and kelp forests. Found in the lower rocky intertidal and subtidally is most common in shallower waters up to 82 feet, though they can rarely be found as deep as 984 feet.

Diet

Voracious carnivore: snails, bivalves, crabs, sea urchins, sea stars, and sea cucumbers

Life History

Sunflower stars are broadcast spawners. Larvae start life as plankton, swimming about and feeding for 50-146 days, before they settle to the bottom and undergo metamorphosis. A juvenile will start with 5 arms but by the time they reach maturity, they can have 24 arms. Diameter up to 3.3 feet; may live up to 65 years.

IUCN Status

Critically Endangered

Ecosystem & Cultural Importance

Sunflower stars are considered keystone predators in areas such as kelp forests. Their predation of sea urchins helps keep their numbers in balance. When Sea Star Wasting Syndrome broke out in 2013 and decimated sunflower star numbers, sea urchin numbers increased dramatically, leading to a decrease in kelp.

In 2023, Oregon Coast Aquarium staff developed a treatment plan for the deadly set of symptoms that have decimated sea star populations as a result of Sea Star Wasting Syndrome (SSWS). There is no known cure for SSWS, but thanks to the efforts of OCAq staff, there is now an effective treatment. Over the last two years, OCAq Aquarist Tiffany Rudek worked to develop a reliable method of treating ill, injured, or stressed sea stars. Read the full article to learn more

Crabs, including red king crabs, morning and Stimpson’s sun stars, glaucous-winged gulls, and sea otters are predators that feed on sunflower stars.
Alaska to California
Now that sunflower stars have started to reappear on the Oregon Coast, you might get lucky and find a juvenile sunflower star while tidepooling.
This is one of the largest and fastest sea stars in the world. It can weigh up to 17.6 lbs, and with its 15,000 tube feet, can move up to 63 inches in one minute. When the smaller predatory Dawson’s sea star attacks a sunflower star, it may drop an arm and flee.

Citations & Other Resources