Ranellidae
An Atlantic Triton snail ( Charonia variegata ) feeding on a sea star
The Triton screw ( Ranellidae ) are a family usually quite large, live exclusively in the sea snails. All representatives of the family are predators that live in tropical and subtropical seas.
Features
The housings are rechtsgewunden and trochospiral rolled up. The mouth is usually oval with edges turned up. The opening can be narrowed and modified by cross ribs, and "teeth" ( protrusions ). Often the lower end is drawn out into a Siphonalkanal. Some of the housing are heavily ornamented. The Adult size ranges from 1.5 to 50 cm. The well-developed foot is very muscular. The head has no or only a short snout. The sensor bases are greatly thickened. Therefore, the fitting to the sensor bases eyes sitting relatively high above the actual head. The housing opening can be closed by a operculum. The family is the extent known dioecious. The ontogenetic development is not uniform within the family. While development usually proceeds through a plankton -eating larva, also Nähreier occur, ie the embryo eats other, mostly unfertilized eggs in the nest and hatch as a complete small animal from its protective envelope clutch.
Way of life
Triton snails feed on prey on echinoderms, tunicates, bivalves and other snails. They live in all tropical and subtropical oceans, mostly in the tidal range in coral reefs, rocky shores and sandy to shallow water. The prey is there mostly paralyzed from the secretions of the major salivary glands and in some cases probably predigested. The prey is then swallowed whole depending on the size or crushed with the radula.
The preferred prey differs within the family Ranellidae: The conches ( genus Charonia ) feed mainly on echinoderms. Cabestana spengleri and Ranella australasia eat almost exclusively sea squirts, septa parthenopium both mussels and sea squirts. Various representatives of the genus Cymatium contrast eat shell -bearing molluscs, depending on the type rather mussels or rather snails. Some Cymatium species, in particular Cymatium muricinum, can become a problem in shellfish farms.
System
Millard (1997) and Riedel (2000 ) represent the family in the superfamily Cassoidea, Ponder & Lindberg (1997) and Bouchet & Rocroi (2006) in the superfamily Tonnoidea. The family name was Cassoidea 1825 erected by Latreille and was thus clearly has priority over Tonnoidea Suter, 1913 (see IRZN ).
The Ranellidae family is divided into two sub- family:
- Cymatiinae Iredale, 1913
- Ranellinae Gray, 1854 Charonia tritonis (also Conch )
- Cabestana cutacea (Linnaeus, 1767)