Tonna galea (Giant tun)


Large cream to brown shell with darker brown lines across the spiral form. The mantle of the snail itself is dark grey and the siphon and proboscises are black.


Unassessed by the IUCN Red list, but a widespread species.


They can be found in the Mediterranean, Western Central Pacific and Atlantic: Belize and North America. They prefer offshore coral reefs, bays and coves, rock, sand and shell habitats, in a depth range of 5-80 meters.


Poecilogonic reproduction, where the parent can produce different types of offspring due to environmental changes.


Up to 23cm.

Prey / Predation

They feed on sea cucumbers, sea urchins, starfish, bivalves, crustaceans and fish. The enclose the prey with their proboscises and inject it with their acidic saliva to kill it.

Special features

This large snail can also release its acidic saliva when it feels threatened. The giant tun is a luminescent species. This is very rare characteristic among the prosobranch gastropods. The animal gives off light that is green-white in colour when it traverses through the water with its foot “well-extended”. The species was previously named Tonna olearium.