page_title: Asterias amurensis
section_title: Description
hierarchical_section_title: Asterias amurensis / Description
caption_attribution_description: 海星（反面）. w:en:Northern Pacific seastar, Asterias amurensis, ventral view. Dorsal view is Image:海星（正面）.JPG
context_page_description: Asterias amurensis, also known as the Northern Pacific seastar and Japanese common starfish, is a seastar found in shallow seas and estuaries, native to the coasts of northern China, Korea, far eastern Russia, Japan, Alaska, the Aleutian Islands and British Columbia in Canada. Two forms are recognised: the nominate and forma robusta from the Strait of Tartary. It mostly preys on large bivalve molluscs, and it is mostly preyed on by other species of starfish. Population booms in Japan can affect the harvest of mariculture operations and are costly to combat.
  This species has been introduced to oceanic areas of Tasmania in southern Australia.
context_section_description: It can grow up to 50 cm in diameter, although this is exceptional and the arms usually grow to 16.1 cm, with the ratio between the length of the arm and the radius of its disc ranging from 3.6:1 to 5.9:1. It has five arms and a small central disk. It can be distinguished from similar species by the distinctive upturned tips of its arms. The underside is completely yellow. It shows a wide range of colours on its dorsal side: orange to yellow, sometimes red and purple. The arms are unevenly covered with small, jagged-edged spines, which line the groove in which the tube feet lie, and join up at the mouth in a fan-like shape.
caption: Asterias amurensis, ventral view
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