The Tonnidae are a family of medium-sized to very large sea snails, known as the tun shells. These are marine gastropod molluscs in the clade Littorinimorpha. The name tun refers to the snails' shell shape, which resembles wine casks known as "tuns". While thin, the shells are also strong and lack opercula. They are found in all tropical seas, where they inhabit sandy areas. During the day, they bury themselves in the substrate, emerging at night to feed on echinoderms (especially sea cucumbers), crustaceans, and bivalves. Some larger species also capture fish, using their expandable probosces to swallow them whole. Females lay rows of eggs that become free-swimming larvae for several months before settling to the bottom. Taxonomy In 2005, these subfamilies were recognized in the taxonomy of Bouchet & Rocroi: Cassinae Latreille, 1825 Oocorythinae P. Fischer, 1885 Phaliinae Beu, 1981 Tonninae Suter, 1913 Bouchet & Rocroi (2005) listed Cassidae as a synonym of Tonnidae Suter, 1913 (1825), following Riedel (1995) in this. However, later Beu (2008: 272) separated the two families. This is in agreement with the action of Thiele (1925) who placed Tonnidae and Cassidae under "Tonnacea", therefore acting as first reviser under ICZN article 24. In this respect, the World Register of Marine Species follows the opinion of Beu. Genera Genera and species within the family Tonnidae include: The subfamily Cassinae has been raised to the rank of family Cassidae Eudolium Dall, 1889 Malea Vallenciennes, 1832 Tonna Brunnich, 1771 Genera brought into synonymy Cadium Link, 1807 : synonym of Tonna Brunnich, 1771 Cadus Röding, 1798 : synonym of Tonna Brunnich, 1771 Cassidaria Link, 1807 : synonym of Eudolium Dall, 1889 Doliopsis di Monterosato, 1872 (non Vogt, 1852; non Conrad, 1865) : synonym of Eudolium Dall, 1889 Foratidolium Rovereto, 1899: synonym of Tonna Brünnich, 1771 Macgillivrayia Forbes, 1852 : synonym of Tonna Brünnich, 1771 Dolium Lamarck, 1801: synonym of Tonna Brunnich, 1771 Parvitonna Iredale, 1931: synonym of Tonna Brunnich, 1771 Perdix Montfort, 1810: synonym of Tonna Brunnich, 1771 Quimalea Iredale, 1929: synonym of Malea Valenciennes, 1832 Further reading Vaught, K.C. (1989). A classification of the living Mollusca. American Malacologists: Melbourne, FL (USA). . XII, 195 pp. References External links Checklist of Mollusca Paleodb