Leptasterias polaris | |
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| Species: | L. polaris |
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| Leptasterias polaris (Müller & Troschel, 1842) [1] | |
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Leptasterias polaris, the polar six-rayed star, is a species of starfish in the family Asteriidae. It is found in cold waters in the northwest Atlantic Ocean and in polar regions.
Leptasterias polaris is a small, slow growing, compact starfish with six arms. The aboral (upper) surface has a covering of blunt spiny plates and is usually some shade of brown or grey. [1] [2]
Leptasterias polaris occurs in the north west Atlantic Ocean from the Gulf of Maine northwards, and in Arctic waters. It has also been found in the Azores and European waters. [1]
Leptasterias polaris is a major predator in the cold waters in which it lives. Young individuals are mostly found on rocks less than 10 metres (33 ft) deep and feed on such bivalve molluscs as the blue mussel ( Mytilus edulis ) and Hiatella arctica . Older individuals move to deeper waters where the seabed is sand or mud and feed on clams such as the Greenland cockle ( Serripes groenlandicus ), Spisula polynyma , the blunt gaper ( Mya truncata ) and the Atlantic jackknife clam ( Ensis directus ) which they dig up with their tube feet. They also eat gastropod molluscs such as the common whelk ( Buccinum undatum ) and the American pelicanfoot ( Arrhoges occidentalis ). In a laboratory study it was found that the starfish detected their prey by odours in the water. Hungry starfish which had not fed for two months, worked their way across the current until their olfactory tube feet, located near the tips of their arms, smelt an edible prey item after which they begin to travel up-current towards the source of the odour. Moving upstream in this way had the advantage that the prey was less likely to detect the approach of the starfish. Well fed starfish wandered in a more random fashion. [2]
Breeding takes place when the water temperature falls to about 2 °C (36 °F) and the day length is at its minimum. Over a period of seven to eight weeks the normally solitary starfish begin to aggregate, eventually some climbing on top of others. The males release sperm which accumulates in a layer on the seabed and the females later release their eggs on top. [3] The females brood the developing eggs for four months [2] but that is probably more to keep them clean and healthy and prevent predation than to speed their development as unbrooded eggs were found in the laboratory to develop at the same rate as brooded ones. [3]
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Oreaster reticulatus, commonly known as the red cushion sea star or the West Indian sea star, is a species of marine invertebrate, a starfish in the family Oreasteridae. It is found in shallow water in the western Atlantic Ocean and the Caribbean Sea.
Luidia clathrata is a tropical species of starfish in the family Luidiidae. It is variously known as the slender-armed starfish, the gray sea star, or the lined sea star. It is found in the western Atlantic Ocean.
Leptasterias hexactis is a species of starfish in the family Asteriidae, commonly known as the six-rayed star. It is found in the intertidal zone of the western seaboard of the United States. It is a predator and is unusual among starfish in that it broods its eggs and young.
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Luidia senegalensis, the nine-armed sea star, is a tropical species of starfish in the family Luidiidae found in the western Atlantic Ocean.
Anasterias rupicola is a species of starfish in the family Asteriidae. It is found in shallow waters in the Southern Ocean and sub-Antarctic Indian Ocean.
The sand star, Luidia foliolata, is a species of starfish in the family Luidiidae found in the northeastern Pacific Ocean on sandy and muddy seabeds at depths to about 600 m (2,000 ft).
Leptasterias tenera is a species of starfish in the family Asteriidae. It is found on the eastern coast of North America.
Astropecten scoparius is a sea star in the family Astropectinidae. It is found in shallow water in the East China Sea and around the coasts of Japan. It is a grey starfish and each of its five arms has a narrow pale margin. It burrows in the muddy sediments on the seabed and feeds on molluscs.
Asterina gibbosa, commonly known as the starlet cushion star, is a species of starfish in the family Asterinidae. It is native to the northeastern Atlantic Ocean and the Mediterranean Sea.
Leptasterias muelleri, the northern starfish, is a species of starfish in the family Asteriidae. It is found in the Arctic Ocean and the northern Atlantic Ocean. It is a predator and scavenger and is unusual among starfish in that it broods its young.
Diplasterias brucei is a species of starfish in the family Asteriidae. It is found in the Pacific Ocean and Southern Ocean. It is a predator and scavenger and is unusual among starfish in that it broods its young.
Allantactis is a monotypic genus of sea anemones, and Allantactis parasitica is the only species in the genus. This sea anemone lives at bathyal depths in the North Atlantic Ocean and has a symbiotic relationship with a gastropod mollusc.
Octopus tehuelchus, commonly known as the Patagonian octopus, is a species of octopus, a marine cephalopod mollusc of the order Octopoda. It is native to shallow waters in the subtropical southwestern Atlantic Ocean. It was first described in 1834 by the French naturalist Alcide d'Orbigny.
Anasterias antarctica, commonly called the Cinderella starfish, is a species of starfish in the family Asteriidae. It is found in coastal waters in the Southern Ocean and around Antarctica.