Rio History: The Tun Shell

Special to the PRESS

Mr. Hathcock, I found a shell while vacationing last September on South Padre Island. I was very surprised to find it in an unbroken condition. My husband says it was probably bought at a shell shop because of its condition. Is this shell normally found on Padre Island?
Thank you,
Marifel Lovell

Hi Marifel,
Congratulations on your find! The shell you found, the Atlantic Tun, belongs to the group of Prosobranchiata and the family of Tonnidae.

The shell, which is thin-walled but very strong, ranges from pale yellow to brown and can grow as long as 7 inches. Because of its light weight, the tun oftentimes floats ashore intact and can be found near the trash or wrack line left by the high tides. The top, or apex, is usually darker and has seven spirals. The snail itself is usually lightly colored with dark toned spots and is larger than the shell it lives in. During the day, it lies buried beneath the silt, venturing out only after dark. It moves about with the help of a large, flat foot, usually in shallow water. A predator, it feeds on shellfish, crabs, sea urchins, sea cucumbers and other smaller animals. It dissolves the shells of other animals by means of an acid secretion from its salivary glands and then pulls its prey from the shell and eats it.

Because their free-swimming larval life is quite lengthy, they range out over great distances. Around 20 species exist worldwide. In North America, the tun can be found from North Carolina to the southern tip of Texas. I’m not sure if they are edible but would imagine there are those chefs who will attest to its flavor.
The name, tun shell, means “cask shell” or “wine jar.” In merry old England, a tun was the volume of wine held in a wooden cask (eight barrels or four hogsheads) whose combined weight equaled our modern ton.
The shell you describe — if purchased in a shell or souvenir shop — would cost around $13.

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