Atlantic Partridge Tun Snail

Tonna pennata

Tonna pennata is a sizable sea snail whose shell can display colors ranging from beige to dark brown, with whitish markings that vary significantly. Its shell has a pear-like shape, featuring a moderately blunt top and a wide, flared opening that constitutes about three-quarters of its total length. The shell's surface is finely striated with shallow grooves between the ribs, and it can grow to a maximum length of around 15 cm. Divers might confuse it with Tonna galea, which has a more rounded form, or Eudolium bairdii, which is generally found at greater depths. The mantle of living specimens is white with brown markings and extends widely as the snail moves. This species inhabits shallow waters across the tropical western Atlantic, the Caribbean Sea, and the Gulf of Mexico, as well as in the eastern Atlantic around the Canary Islands and Madeira. It is typically found in reef environments, on coral, rocky substrates, sandy bottoms, and seagrass meadows, usually at depths ranging from 0 to 13 meters. As a predator, Tonna pennata primarily targets sea cucumbers, particularly those in the family Stichopodidae, but it also preys on bivalve mollusks and fish. The snail utilizes a long eversible proboscis to envelop smaller prey or immobilize larger ones by secreting saliva that contains sulphuric acid. This allows it to effectively attack animals much larger than itself. Its reproductive strategy includes broadcast spawning, with embryos transitioning into planktonic larvae before maturing into adults. Encounters with this species during dives can be engaging, as divers may witness its distinctive feeding habits and the varied textures of its shell.