Every Seashell Has a Story: The Mole Cowrie

by B. N. Sullivan

Cowrie shells are prized by collectors for their shiny china-like surface, and beautiful colors. Hawaii has many cowrie species. Some are endemic -- found only in Hawaii -- while others are more widely distributed around the Indo-Pacific region. Curiously, though, a number of the cowrie species that are found elsewhere as well as in Hawaii happen to grow to a larger size in Hawaii. One of those is the Mole Cowrie (Cypraea talpa), pictured at left.

Decades ago, on an early dive trip to the Red Sea, I had found a small Mole Cowrie shell and added it to the collection. Back home in Hawaii, we found pieces of broken Mole Cowrie shells with maddening frequency, so we knew they were around, but for the longest time we never could find a whole Mole Cowrie -- dead or alive.

One day, finally, we saw a large Mole Cowrie shell, all by itself on the surface of the sand. We hurried toward it, anxious to pick it up and examine it to see if it was alive. But before we reached it, a Spotted Eagle Ray appeared out of nowhere, swooped down, and snatched the Mole Cowrie from the sand. The ray quickly swam off, still munching its snack, and expelling sand and broken pieces of shell through its gill slits! Of all the nerve!

This time our disappointment was short lived. Just a few weeks later we were heading back to the reef after another deep dive out on the sand flat at Puako. We began to gradually ascend as we swam shoreward. As we passed over a large boulder that we used as a landmark on our route, I was amazed to see beside it a large, whole Mole Cowrie shell. Since we had begun our ascent, we were already a good 5 meters above the rock, but I couldn't resist dropping back down to check out the Mole Cowrie.

Since I had my camera in hand, the first thing I did was take a photo of the Mole Cowrie where it sat on the sand, without distrubing it. That's it in the photo on this page. A nasty looking Viper Moray eel that was hiding in a crevice near the base of the big rock poked its head out as I snapped the photo of the cowrie shell. The eel -- mouth open, eyes glaring -- looked right at me as I reached for the shell. I wondered if the eel would grab the shell, just as the Eagle Ray had done weeks before. But no, the eel tucked itself back into its crevice, so I picked up the shell. As I picked it up, I could tell that it was very light: it was empty!

I looked up at Jerry who was still hovering 5 meters above where I knelt and gave him the 'okay' sign. I popped the shell into my trusty little mesh bag and we swam back to shore with our new treasure.

Like most cowries, the Mole Cowrie forages at night. When the snail is active, it slides its fleshy mantle up over the outside of the shell until it is completely covered. The secretions from the mantle are what keep the surface of the shell so smooth and shiny. Here is a link to a photo of a live Mole Cowrie with the mantle extended, so you can see what it looks like.