Tonnidae

Tonnidae is a family of large predatory sea snails, commonly known as tun shells or tun snails. These marine gastropod mollusks belong to the order Littorinimorpha. They are characterized by their large, globular, and often thin shells, which are typically inflated and rounded. The aperture of the shell is usually wide and extends to the base, with a short siphonal canal. The outer lip is often everted.

The shells of Tonnidae are typically light in color, ranging from white to pale yellow or brown, and may be marked with spiral bands or other patterns. Some species exhibit nodules or spines on their shell surface. The interior of the shell is usually glossy. The animals themselves are soft-bodied and have a muscular foot for locomotion. They possess a radula, a ribbon-like structure with teeth, which they use to rasp food.

Tonnidae are found in warm and tropical seas worldwide, inhabiting shallow to moderately deep waters. They are often found on sandy or muddy bottoms, where they burrow or forage. These snails are carnivorous, feeding primarily on echinoderms such as sea urchins and starfish, as well as other invertebrates. They are known to be active hunters, using their radula to bore into the shells of their prey.

The family Tonnidae contains several genera, including Tonna,malea, and Euspiralix. Many species are quite large, with shell lengths exceeding 20 centimeters, making them some of the largest gastropods in existence. Despite their size, their shells are often relatively lightweight due to their thinness.