North Pacific starfish
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North Pacific starfish ( Asterias amurensis ) |
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| Asterias amurensis | ||||||||||||
| Luetken , 1871 |
The North Pacific starfish ( Asterias amurensis ) is a species of starfish from the order of the pincer stars (Forcipulatida), which is native to the coasts of China , Korea , Russia and Japan . It has been spread to other parts of the world as an invasive species , including Australia , North America and Europe .
features
The North Pacific starfish reaches a diameter of up to 50 cm and has five arms, the ends of which are bent upwards. The top is orange to yellow, sometimes purple in color. The arms are provided with irregularly arranged spines. A row of spikes in the shape of a fan runs from each arm to the center of the starfish. A series of spines also run along the ambulacral furrow on the underside of each arm .
habitat
The North Pacific starfish is native to the coasts of the Pacific in Japan, Russia, northern China, and Korea. As an invasive species , it occurs on the southern coast of Australia, in Tasmania , Alaska , the Aleutian Islands , Europe and Maine (USA). It occurs in estuaries and sheltered areas of the coastal zones up to 220 m depth and prefers temperatures of 7ºC to 10ºC, but it is found in Australia in coastal areas with an average of 22ºC warm water. It can withstand temperatures from 0ºC to 25ºC and a salt content of 1.87 to 4.10 percent.
nutrition
Asterias amurensis mainly eats mussels , but also fish eggs and numerous animals such as snails , barnacles , sea urchins , starfish and decapods . Cannibalism occurs when there is a lack of food. The starfish can also dig up buried animals. The prey is digested extraintestinally .
Reproduction
Like most starfish, Asterias amurensis is separate sexes. During the mating season, females and males come together and release their germ cells into the water. This is between January and April in Japan and between June and October in Russia and Australia. The eggs fertilized in the open water develop into a Brachiolaria larva via a freely swimming Bipinnaria larva. Depending on the temperature about 41 to 120 days after fertilization, the larva anchors itself with its adhesive disc on the ground and undergoes the metamorphosis into a starfish.
Both males and females become sexually mature with a body diameter of about 3.6 cm to 5.5 cm. Females can be recognized by their orange ovaries and the eggs that are constantly being released into the water for around 5 to 6 months a year. About 10 to 25 million eggs are produced by one female. Males can be identified by the yellowish-brown color of their testicles during the 6 months of their sexual productivity per year.
Enemies
The North Pacific starfish has few predators. King crabs ( Paralithodes camtschaticus ) have been seen eating North Pacific starfish in Alaska . In laboratory tests, the conch horns ( Charonia ) preferred Asterias amurensis as prey over other species. The Japanese sun star ( Solaster paxillatus ) is another possible enemy .
Ecological importance
As an invasive species , Asterias amurensis has drastically reduced the populations of native species of molluscs , echinoderms, and crustaceans in many locations . Due to the consumption of fish eggs, it is associated with the decline in the endangered handfish Brachionichthys hirsutus in Australia . The starfish spreads as a larva in the ballast water of ships. Due to the great threat that this starfish poses for biodiversity, Asterias amurensis has been included in the " List of the 100 of the world's worst invasive alien species".
Web links
- Foram Shah, Shikha Surati: Asterias amurensis . Animal Diversity Web, 2013.
- Shyama Pagad: Asterias amurensis . Global Invasive Species Database, 2010.
Individual evidence
- ↑ 100 of the world's worst invasive alien species . 2013 update. Global Invasive Species Database. Retrieved October 20, 2015.