The tiger cowrie (Cypraea tigris) is one of the larger species of cowrie. They are marine snails in the family Cypraeidae. They are an extremely attractive sight as they move across the reef. They are nocturnal and are only seen on the move at night. During the day they can be seen on the reef holed up in their shells, sometimes in the open.
Roughly egg-shaped, the shell is glossy on the exterior and measures up to 15 cm in length. Most are however in the 10 cm range. The exterior of the shell is a pale whitish color covered with a large number of dark brown or blackish spots. On the lower section of the shell it is a whitish color and the opening is lined with tooth-like serrations.
The mantle extends upwards from each side and the two sections meet on the top of the shell so as to cover it completely. As can be seen in the images the mantle is a dark brown or black color with lighter brown spots. The mantle can withdraw completely into the shell for protection. There are numerous thin projections which are white tipped. The coloration varies greatly from location to location. There are three different specimens in the images and the color variations between each are noticeable.
IN THE WILD
Tiger cowries are seldom seen with their mantles out during the day and are usually in hiding during daylight. On rare occasions they are seen out in open with the mantle retracted. Presumably because there was no convenient hiding spot. They are preyed upon by some species of fish, octopus which bite through their shells and cone shells.
The tiger cowrie is found across the Indo-Pacific region, from the east coast of Africa including Madagascar to Micronesia and Polynesia, the Coral Sea and the Philippines. Along the Australian Coast they are found on the west coast of Australia, including Lord Howe Island. They are found in East Africa from depths of 1 meter to 40 meters. They are usually found on reefs but have also been seen on sandy bottoms and in grass beds.
The adult tiger cowrie eats coral, sponges and various invertebrates, while the juveniles eat algae.
The tiger cowrie is either male or female and after mating the female will lay the eggs and cover them with their foot. This is unusual amongst gastropods and is probably one of the reasons they are such a successful species. Once the eggs hatch they enter a planktonic stage and then develop into young adults. Interestingly once a cowrie has reached its adult size the shell stops growing.
Once common throughout most of its range, it is now much less common due to shell collecting and destruction of its habitat through development and other activities such as dynamite fishing, especially in shallower areas.
Carvings or cameos have been cut into their shells since at least Roman times because some decorated shells have been found in Roman ruins. The sale of shells to tourists continues to this day although controls over the export of these shells has reduced this practice. The shells however are still popular amongst shell collectors. They are however far more beautiful alive.
They can be kept in aquariums and are in demand for rock type aquariums. Because of their size they can push rocks over if they are not well bedded. Because of their predatory nature and diet of sponges and soft corals and other marine organisms they are not suitable for reef tanks. It should also be remembered that they are nocturnal and feed at night and as such may not be seen much.