Cypraea tigris, Marshall Islands

Cypraea tigris Linnaeus, 1758
Tiger cowry, 59-108mm

The shell of Cypraea tigris is typically white with dark spots, but specimens vary from nearly pure white to nearly pure black. Living animals can be found under rocks on lagoon interisland intertidal and shallow subtidal reefs such as that at Ebwaj Island or along the reef between Ennubuj and South Pass. Specimens are also sporadically common exposed on the hard reef flat above the seaward reef dropoff. Occasional specimens are found on lagoon pinnacles. Kwajalein's smallest specimens come from a series of quarries and the surrounding reef between Roi and Namur Islands. Seaward reef specimens have been found eating a jet black sponge that grows in the open on the hard reef substrate. This is the only large cowry that is often found out in the open during the day, although then it is usually retracted and inactive. At night the mantle extends and it wanders over the reef grazing. It is the second longest cowry in the Marshalls, second only to Chelycypraea testudinaria, which the tigers typically exceed in girth. The empty shells at the bottom of the page illustrate some of the variation in the shell coloration. The line that runs across the top of the shell from front to back is where the two lobes of the mantle meet when it covers the entire shell. This species has a wide distribution throughout the Indo-Pacific. The subspecies in the Marshalls is Cypraea tigris pardalis, which is differentiated from the primarily Indian Ocean Cypraea tigris tigris primarily through DNA studies.

An exceptionally dark specimen with a yellow mantle was found under the edge of the sea anemone Stichodactyla haddoni in a Halimeda patch on a sandy lagoon slope.

The animal below has its mantle nearly fuly extended. Having said above that the dorsal line is where the mantle lobes from right and left typically meet, it is apparent that in the specimen below the right lobe (front of the photo) has extended over the dorsal line. Obviously, they can arrange the mantle as they choose. The mantle is usually grayish in color with small longitudinal gray and white lines, occasional darker blotches, and spike-like gray papillae that are tipped with white.