Cowries have shells that inspire collectors, but the living animal is equally interesting.
Many cowries live on or alongside coral reefs where they usually feed by night on encrusting plants and animals. Cowries are related to the slugs and snails that live on land, and have the same rasp-like structure which they use to scrape their food off the rocks. All cowry shells are smooth and shiny because the fleshy cloak that covers them at night removes anything that tries to settle on them and deposits a thin layer of fresh shell material. At night, when the shell is fully covered by the flesh mantle, cowries look like many sea-slugs. Their mantle has finger-like projections which are thought to help with extracting oxygen from the water and also to help break up the outline of the animals and camouflage them. When the day arrives, or if the cowry is disturbed, the entire fleshy mantle can be withdrawn into the shell, which is often painted subtly to give daytime camouflage on the reef.
There are more than 200 species of cowry and they are one of the most avidly collected of all shells, with enthusiast sometimes paying a lot of money for a good specimen of a rare species. One of the most highly prized of all is the Golden Cowry Cypraea aurantium. This large cowry is a deep gold in colour when freshly collected, and this colour deepens with age. There is a specimen in the Natural History Museum in London which is very old and has a rich patina which makes it almost priceless. This shell is not on general display, but I was lucky enough to see it once when I was working on an ‘Encyclopaedia of Shells’ – it is stunning! The Golden Cowry is endemic to Fiji and was a symbol of kingship there; it was a capital offence for a commoner to be found in possession of this shell!
The Snakeshead Cowry, Cypraea caputserpentis must be my personal favourite, it is very common and only about one inch long, but the rich chocolate colouring with irregular creamy-white spots makes it one of the most beautiful in my eyes. My wife and I gave these shells as ‘favours’ wrapped in tulle at our wedding (back in the 1970’s), and an ageing Aunt-in-law tried to eat one, thinking they were sugared almonds. She broke a tooth and was not very amused.
I have never seen the living animal, but the mantle is described as ‘olive brown with irregular spots or flecks of yellow, green, or white and covered with frilly, branched extensions’. This must be a perfect camouflage against the reef. The Snakeshead Cowry likes to feed on algal films and could probably be kept safely in a Reef Tank.
Collect cowries by all means, but if you buy them make sure they were collected in a way that did not destroy the coral reef.
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