Northern Pacific Seastar
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
doesnt 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
Invaded Areas: South Eastern Australia and the Tasmanian
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.