Velutina velutina

Velutina velutina

Velutina velutina is a snail from the family of Velutinidae in order Sorbeoconcha who lives among other things, in the North Sea and the Baltic Sea Circumboreal. It feeds on ascidians.

Features

The ear-shaped, ungenabelte, very thin -shelled snails House of Velutina velutina, which up to 2.6 cm in length achieved in adult snails 1.4, has rapidly increasing whorls and an egg-shaped case mouth with a contiguous border. The white shell is surrounded by a gray-brown, fibrous, fairly thick shell skin.

The body of the screw to a length of 1.5 to 5 cm. The animal can withdraw into his shell completely.

Dissemination

Velutina velutina occurs Circumboreal on the Mediterranean Sea, the Atlantic Ocean and the Arctic Ocean. It occurs both in the North Sea and in the Baltic Sea and is near Helgoland, located in the Bay of Kiel and in the Fehmarn Belt. Other deposits are found, among others, off Greenland (West Greenland ), Canada ( Labrador, Nova Scotia, New Brunswick) and the USA ( Maine, east coast as far south as Cape Cod in Massachusetts, west coast from Alaska to Monterey County in California).

Way of life

Velutina velutina is sometimes found in the intertidal zone under rocks and in other protected places, often on rocks and gravel below the intertidal zone down to depths of at least 225 m. But you also lives in sandy- muddy substrates, as far as there exist solitary ascidians.

Unlike representatives of the allied genus Lamellaria is a simultaneous hermaphrodite Velutina velutina, but self-fertilization is prevented by various morphological, physiological and behavioral mechanisms.

The food of Velutina velutina consists of solitary ascidians, including representatives of the genera Styela, Ascidia, Phallusia and Cynthia, in the Baltic Sea, for example, Styela coriacea. The victims are blown out from the inside. The worm is also very secretive sea squirts, which suggests that the prey is found by chemical stimuli. In the empty shells of sea squirts eaten the worm lays its egg capsules, which hatch veliger larvae of the type Echinospira. Until the metamorphosis to the finished screw a pelagic phase follows.