Leviathan cowries: Becoming scarce in Hawaii?

by B. N. Sullivan

Here is another favorite from our seashell collection. One of the larger cowries found in Hawaii, its name is apt: Leviathan (Cypraea leviathan).

This one has been in our collection for a long time. I found it in the mid-1980s at Pupukea on the north shore of the island of Oahu. This one is 6.6 cm in length (roughly 2.5 in).

We used to see Leviathan cowries quite regularly, but we haven't seen any at all in quite awhile, alive or empty. These guys live in relatively shallow water, so they are (or were) relatively easy for snorkelers, divers -- and even waders -- to spot. We fear that we're not seeing them these days because too many live ones have been taken by collectors, leaving too few to reproduce and maintain the population.

Older reference books about seashells list Leviathan cowries as endemic to Hawaii. More recently these shells have been recorded in a number of other locations in the Indo-Pacific region, so while we still can say that they are indigenous to Hawaii, they are no longer considered to be Hawaiian endemics.

Leviathan cowries are heavy shells; they definitely are not fragile. And like almost all cowries, they have a wonderful china-like look to them.

One of the distinctive features of the shells of Leviathan cowries is a row of violet teeth bordering each side of the aperture on the underside of the shell. You can see those unusual violet teeth clearly in the second photo on this page. There are several other cowries in Hawaii that have marking similar to the Leviathan, but they are smaller -- and they do not have those wonderful violet teeth!

Another distinctive feature of Leviathan cowries has nothing to do with the shell, but rather with the snail that secretes and inhabits the shell. Readers may recall the photos of a live Tiger cowrie that we posted here on The Right Blue earlier this year. When the creature's mantle was extended over the shell, you could see that it had rubbery-looking thingies sticking out all over it. Those are called papillae. Well, the papillae of Leviathan cowries are quite different. They are spiky clumps that look like little bushes!

The papillae on the mantle of the Leviathan are difficult to describe, and I don't have a photo of a live one to post. Fortunately there is a video on YouTube that shows a live Leviathan with its mantle extended over the shell. You can see the weirdly shaped papillae on the mantle.

Here is makuabob's video, Meet Cypraea leviathan:

If the video does not play or display properly above, click here to view it on YouTube.