Giant tun - Tonna galea (Linnaeus, 1758) - Cyprus

Family Tonnidae

Tonna galea, commonly known as the giant tun, is a species of marine gastropod mollusc in the family Tonnidae (also known as the tun shells). This very large sea snail or tun snail is found in the North Atlantic Ocean as far as the coast of West Africa, in the Mediterranean Sea and the Caribbean Sea. The species was first described by Carl Linnaeus in 1758

The shell of adult Tonna galea is very large, with an average height of 6 inches (150 mm). In terms of its weight however, the shell is very much lighter than the shell of most other large sea snails. The aperture of the shell is "distinctly round" and wide,^[4] Shells of this species are often yellow-white in colour, with a blotch or band pattern that is brown.^[3] The shell is thin and inflated, but still relatively solid and durable.

Tonna galea possess large salivary glands. The structure of these glands was first described and detailed by Heinrich Weber in 1927.Furthermore, the Giant Tun is also a luminescent species; this is an extremely 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"

This large sea snail is found in the North Atlantic Ocean (specifically the Canary Islands and Madeira), the Mediterranean Sea, the  Caribbean Sea, and in the waters off the coast of Angola, Cape Verde and West Africa. The preferred habitat for this species isseabeds that are muddy or sandy with seagrass beds. In the Mediterranean, these snails are typically found at depths ranging from just beneath the surface to 120 metres (390 ft).

Tonna galea has been placed on Annex II of both the Berne Convention on the Conservation of European Wildlife and Natural HabitatsNand the Protocol of the Barcelona Convention for Protection against Pollution in the Mediterranean Sea. In spite these designations, it continues to be "exploited"

Information on the biology and life history of Tonna galea is scarce, due to the fact that the species has only rarely been studied. It is carnivorous, and utilizes its two proboscises—located on top of its head—to envelop its prey, which primarily consists of sea cucumbers. To a lesser extent it also feeds on sea urchins, starfish. fish, bivalves and crustaceans. As a defense mechanism, the snail will squirt its highly-acidic saliva when disturbed. This contains approximately 2–5% sulfuric acid, which is used to kill its prey. The presence of this acid was recorded by Franz Hermann Troschel in 1854

From Wikipedia, the free encyclopedia

Photos by George Konstantinou
Underwater photos by Kostas Aristeidou
Photos and video by Costas Constantinou