British Beasts | Cowries
British cowries are small but beautifully formed
I remember, as a kid, scouring beaches for their pink shells (actually, I still do), prizing them above all others. Worldwide, cowries seem to have a similar effect on humans, being regarded as symbols of luck and fertility. They have even been used as currency in some countries, including India, China and Ghana. Tropical cowrie shells are hard and smooth with a high gloss, often with beautiful patterns and colours. This makes them highly prized as jewellery and for use in ceremonies, as well as by shell collectors; some species have become rare through over-collecting of live specimens.
Our British cowries (Triviidae) are in a separate family from tropical ones (Cypraeidae), but they share the same shell shape and slit-like opening beneath. Living cowries wrap a skirt of tissue, known as the mantle, around the shell. This continually deposits new enamel on the outside, and explains why cowrie shells are so beautifully glossy. Most other molluscs deposit new shell on the inside, so the inside stays shiny while the outside becomes worn. Young cowries actually start with a spiral shell, like other snails, but in adult animals the last whorl completely overtakes the original spire. Space is made for the growing animal by dissolving the older shell internally.
At the front end, the mantle rolls up into a long siphon, which takes in water for respiration, while two tentacles, with tiny eyes at the base, sense the water for chemical clues to dinner. Both our little cowries eat colonial sea squirts. Female cowries lay their eggs, 800 to a capsule, inside a hole they have eaten into a sea squirt colony. After a few weeks, tiny larvae emerge into the water, spending several months in the plankton before settling on the sea bed.
In northern Scotland, particularly in Caithness and Orkney, cowries are known as ‘groatie-buckies’. ‘Buckie’ is a Scottish name for whelks and, given the association of cowries with money, I had always assumed that ‘groatie’ came from the old groat (a thick coin named from the Dutch groot, meaning ‘great’ or ‘large’).
However, in one of the fascinating detective chains that ensure I never get bored with writing British Beasts, a search for the origins of the name ‘groatie-buckie’ went off on all sorts of tangents. Many threads led to the village of John o’ Groats, famous chiefly for being at the opposite tip of the British mainland to Land’s End. It takes its name not from the coin, but from the Dutchman Jan de Groot, who built a house there in the 15th century.
In former times, generations of local ‘shore-sellers’ spent hours searching the beaches of John o’ Groats to find cowrie shells to sell to tourists. Eighty of the tiny shells were required to make a necklace, and between 400 and 500 necklaces could be sold during the tourist season at four shillings and sixpence each; a substantial sum in Victorian and Edwardian times.
beast at a glance
Spotted cowrie Trivia monacha Arctic cowrie Trivia arctica
Known haunts: Rocky reefs, occasionally on rocky seashores. Cowrie shells are often found washed ashore from nearby rocky reefs.
Best place to see: Both species can be found all around Britain, especially on western coasts. The Arctic cowrie is more common in the north.
Likely to appear: Present all year.
Distinguishing features: British cowries are small, oval molluscs with glossy, ridged shells, pinkish-brown on top and white beneath, with a slit-like opening. The shells of spotted cowries have three dark spots on the upper surface. The shell is often hidden by a mantle, which has spots or blotches that can be confused with those on the shell itself. The mantle and siphon of the spotted cowrie are often bright yellow, red, orange or brown, while those of the Arctic cowrie are paler.
Size: Spotted cowrie shells are up to 12mm long, while those of Arctic cowries reach 10mm.