''Luidia sarsii'' is a species of
starfish
Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish ...
. Sand colored with a velvety texture, the species expresses
pentamerism
Symmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. For example, take the face of a human being which has a pla ...
or pentaradial symmetry as adults. The five gently tapering arms have conspicuous bands of long white marginal spines in groups of three. ''Luidia sarsi'' grow to approximately 20 cm across and are found in deeper water (20 m+) from Norway to the Mediterranean but in deep colder water in the south. They are usually found on muddy sediment and are most active at night, burying themselves under the sand during the day. ''Luidia sarsii'' larva develop from a fertilized egg and are unique in a number of respects. The larva of the species attains an unusual size (up to 35 mm) and a juvenile starfish develops inside the larva. During
metamorphosis
Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...
the juvenile migrates to the outside and detaches from the swimming larval
bipinnaria stage. The larva continues to live separately for several months.
References
Further reading
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Luidia
Fauna of the Atlantic Ocean
Fauna of the Mediterranean Sea
Animals described in 1846
{{Asteroidea-stub