Northern Pacific Sea Star

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[Image: Serena Cox, NIWA].

The Northern Pacific Sea star (Asterias amurensis Lütken, 1871)

Status in New Zealand

Not in New Zealand.

Legal status:

Unwanted organism.

Description

The Northern Pacific sea star is a large star fish (up to 50cm in diameter) that is native to the coastal waters of the north-western Pacific Ocean, including Japan, Russia, North China, and Korea. It has been introduced inadvertently to Australia where it occurs in large numbers in several estuaries and embayments in the states of Tasmania and Victoria. The Northern Pacific sea star is normally found in shallow water but occurs from the intertidal area through to the subtidal as deep as 200 m. It can be found on muddy, sandy, pebbly seabeds as well as on rocks and man-made surfaces, even mussel lines. You would not normally see it in areas with high wave action.

Why is it a problem?

The Northern Pacific sea star is a voracious predator that will feed on a wide variety of other marine animals, including shellfish, crabs, worms and even dead fish and other sea stars. Because it can occur in very large numbers and also feeds on wild and farmed shellfish, it could have a serious impact on our aquaculture industry and our marine environment generally.

 

View this astonishing footage on Youtube of the Northern Pacific Sea Star at Mornington Pier near Melbourne, Australia [Pang Quong]

What do they look like?

Key features:

The North Pacific Sea star generally has five arms which have pointed and often up-turned tips. The arms join onto a central disc and are covered by clumps of small chisel-like spines. Adults are ~10 cm diameter, with individual arms sometimes up to 40-60 mm long. The topside of the seastar varies in colour and can be yellow, orange or have purple markings. Underneath, they are generally yellow with spines in a single line either side of the groove where the tube feet lie.

Download an identification guide

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A yellow colour variant of the Northern Pacific sea star [Serena Cox, NIWA]

 Find out more about this species