Velutina velutina
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Velutina velutina |
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| ( OV Müller , 1776) |
Velutina velutina is a snail from the family Velutinidae in the order Sorbeoconcha , whichlives circumboreally in the North Sea and the Baltic Sea ,among others. It feeds on sea squirts .
features
The ear-shaped, unholed, very thin-shelled snail shell of Velutina velutina , which in adult snails reaches 1.4 to 2.6 cm in length, has rapidly increasing whorls and an egg-shaped housing mouth with a continuous edge. The white shell is surrounded by a gray-brown, fibrous, rather thick shell skin .
The body of the snail reaches a length of 1.5 to 5 cm. The animal can completely withdraw into its snail shell.
distribution
Velutina velutina occurs circumboreally in the Mediterranean , Atlantic and Arctic Oceans . It occurs in both the North Sea and the Baltic Sea and can be found near Helgoland , in the Bay of Kiel and in the Fehmarnbelt . There are other occurrences off Greenland (West Greenland), Canada ( Labrador , Nova Scotia , New Brunswick ) and the USA ( Maine , east coast south to Cape Cod in Massachusetts , west coast from Alaska to Monterey County in California ).
Way of life
Velutina velutina can sometimes be found in the intertidal zone under rocks and in other protected areas, more often on stones and gravel below the intertidal zone down to a depth of at least 225 m. But it also lives on sandy-silty subsoil, as far as solitary sea squirts occur there.
Unlike members of the related genus Lamellaria , Velutina velutina is a simultaneous hermaphrodite , but self-fertilization is prevented by various morphological, physiological and behavioral mechanisms.
The diet of Velutina velutina consists of solitary sea squirts , including representatives of the genera Styela , Ascidia , Phallusia and Cynthia , in the Baltic Sea z. B. Styela coriacea . The victims are eaten up from within. The snail also finds sea squirts living very hidden, which suggests that the prey is found by chemical stimuli. The snail lays its egg capsules in the eaten shells of the sea squirts, from which Veliger larvae of the Echinospira type hatch. A pelagic phase follows up to the metamorphosis to the finished snail .
literature
- Manfred Diehl (1956): The predatory snail Velutina velutina as enemy and brood tenant of the Ascidie Styela coriacea . Kiel marine research. 12: 180-185.
- Donald Putnam Abbott, Eugene Clinton Haderlie: Prosobranchia , in: Robert Hugh Morris, Donald Putnam Abbott, Eugene Clinton Haderlie: Intertidal Invertebrates of California . Pp. 230-307, here pp. 273, 13.66: Velutina sp., V. velutina (Müller, 1776), Smooth Velutina . Stanford University Press, 1st ed., Stanford (CA, USA) 1980. ( Google Books )
- Heinrich Adolf Meyer, Karl August Möbius: Fauna of the Kiel Bay . Published by Wilhelm Engelmann, Leipzig 1872.
Individual evidence
- ↑ a b Erwin Stresemann (Ed.): Excursions fauna. Invertebrates I. SH Jaeckel: Mollusca . People and knowledge, Berlin 1986. P. 131. Lamellariidae: Velutina velutina OF Müller.
