European Cowrie

Overview

The European cowrie is a small, predatory marine snail recognized by its glossy, lemon-shaped shell featuring distinct transverse ridges. Often found in temperate rocky coastal environments, this species is frequently associated with colonial sea squirts, which serve as both its primary food source and habitat.

Appearance

Adult shells are typically reddish-brown with three characteristic dark spots arranged in a central line, though juvenile shells are often pale or white. The shell surface is marked by 20–30 strong, sometimes bifurcated, transverse ridges. When active, the animal extends a brightly colored mantle—often in shades of yellow, red, or orange—that can almost entirely envelop the shell. The foot may also display white striping, and the siphon and tentacles are typically a vibrant orange.

Distribution & habitat

This species is native to the northeastern Atlantic Ocean, including the North Sea, the British Isles, and the Mediterranean Sea. It prefers rocky substrates in the lower intertidal zone and shallow sublittoral waters, often sheltering under boulders or stones. It is rarely found in soft sediment areas where its preferred colonial ascidian prey, such as Botryllus and Diplosoma species, are absent.

Feeding

As a carnivore, the European cowrie feeds on colonial sea squirts. It uses its specialized mouthparts to bore into these organisms to consume them.

Reproduction

Breeding occurs from late spring through summer. Females deposit flask-shaped egg capsules, each containing up to 800 eggs, onto the colonial ascidians they inhabit. Planktonic larvae emerge from these capsules after several weeks.