Wentletrap

Scalare case of Epitonium

The spiral staircase snails or simply spiral staircases ( Epitoniidae ) are a large family of mostly small to medium-sized, exclusively marine snails, which are distributed worldwide. They feed as predators or ectoparasites of sessile cnidarians.

Features

The dextral, thin-walled and fragile, more or less tower-shaped housing of the spiral staircase snails have tightly coiled, not or hardly related to each other, strongly convex whorls, forming a high conical spiral. In many species, particularly pronounced in the genus Epitonium, they have over the snail shell on running thin, sheet-like axial ribs. In some species, as in the genus Cirsotrema who have housing next axial ribs and spiral extending bands. Often the houses have a deep navel. The case mouth is round or oval. The round, horny operculum has only a few turns and closes the mouth tight.

Besides of the radula, the screw pine have for cutting or biting. The worm eat cnidarians. For large prey or host animals large pieces are more or less cut out, swallowed smaller prey as a whole. The snails live on their host animals or in the sand or gravel around.

The snails are first males and females later. After internal fertilization, the female lays the eggs in capsules, which are covered with sand. The capsules are mounted along an elastic yarn, which is deposited from a gland in the foot of the animal. From these hatch veliger larvae, which undergo a prolonged period as zooplankton and are so widespread.

Occurrence and distribution

The Epitoniidae are common in all tropical, subtropical, temperate, Arctic and Antarctic oceans. They live both in shallow water and at great depths, sometimes up to 6000 meters water depth.

In the North Sea, the family is represented among others by the congregation spiral staircase ( Epitonium clathrus ).

System

After Bouchet and Rocroi ( 2005), the family Epitoniidae one of three families in the superfamily Epitonioidea. She has several hundred species in about 30 genera.