European cowrie  (Trivia monacha)

Not threatened (2).

The European or spotted cowrie is a marine mollusc that has an egg-shaped glossy shell featuring many transverse ridges with a long, narrow aperture on the underside (2). The upper surface of the shell is usually a reddish brown colour, and has three characteristic spots that allow the species to be identified easily (3). The head, tentacles, foot and body of this mollusc are brightly coloured; they may be red, yellow, green, brown or orange (3).

This cowrie is found around most British coasts (2). It is found as far south as the Mediterranean, and reaches the extreme north of its range in western France and Britain (3).

Found in association with its prey, colonial sea squirts (ascidians) including Botryllus schlosseri and Botylloides leachi (2) on the lower shore and in the sublittoral zone of rocky shores. It may also live in estuaries (3).

This species feeds on sea squirts by biting lumps from the zooids(3). Breeding occurs in late spring and summer. The sexes are separate and fertilisation takes place internally following copulation. Females lay their eggs into sea squirts by biting holes in the colonies and then laying their flask-shaped egg capsules (each containing around 800 eggs) into the hole. After a few weeks the larvae hatch. They are free-swimming and pelagic for around a month (2) and are usually found in coastal waters during the summer (3).

In some parts of the world, large cowrie shells were once used as currency, but this did not occur in Britain. The word cowrie originates from the Hindu and Urdu languages, as cowries are very common in the Indian Ocean (4).

This species is not currently threatened.

Conservation action has not been targeted at this species.

For more information see: Fish, J.D. & Fish, S. (1989) A student’s guide to the seashore. Unwin Hyman Ltd., London.

• Larvae: stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
• Pelagic: inhabiting the open oceans.
• Sublittoral: a marine zone between the littoral zone (the shallow zone where light reaches the bed, subject to submersion and exposure by tides) and depths of around 200m.
• Zooid: an individual colony member of colonial invertebrates, such as bryozoans.

1. NBN Species Dictionary (November 2002) http://yaw.nhm.ac.uk/nhm/
2. Fish, J.D. & Fish, S. (1989) A student’s guide to the seashore. Unwin Hyman Ltd., London.
3. Gibson, R., Hextall, B. & Rogers, A. (2001) Photographic Guide to the Sea & Shore Life of Britain and North-west Europe. Oxford University Press, Oxford.
4. Buczacki, S. (2002) Fauna Britannica. Hamlyn, London.