Northern Pacific Seastar
(Asterias amurensis)

Description: This is a large, hardy seastar that can grow to 40-50 cm in total diameter but has a relatively small central disk. The tips of the arms are distinctively turned upwards. The body is yellow and is sculptured with red and purple pigmentation on its top surface, while the underside is uniformly yellow. The native ocher star (Pisaster ochraceus) is superficially similar, but generally doesn’t have such strongly upturned arm-tips. The native pink seastar (P. brevispinus) can be distinguished by its pink color, and the giant spined seastar (P. giganteus) by the distinctive blue rings surrounding spines on its top surface.

Habitat: This species is typically found in shallow water of protected coasts. It can tolerate a wide range of temperatures, and, unusual for an echinoderm, a wide range of salinities. Unlike the native Pisaster species, Asterias is often found in estuaries.

Origin: Northern China, Korea, Russia, Japan, and far northern Pacific waters.

Invaded Areas: South Eastern Australia and the Tasmanian coast.

Concerns: Invasive Asterias number in the millions on parts of the Australian coastline. A voracious predator particularly on bivalves, this seastar has been shown to impact oyster culturing and shellfish production in these regions. Since estuaries on our coast do not have any native seastar predators, our native bivalves might be particularly vulnerable to an invasion by Asterias.. Other native consumers of bivalves might also suffer from competition with rapidly burgeoning seastar populations.