These include bivalve molluscs, polychaete worms, barnacles, gastropod molluscs, other echinoderms and carrion. Specialized predatory gastropod molluscs prey on these cnidarians. Invertebrates including cephalopods, crustaceans, and bivalve or gastropod molluscs are hunted or farmed for food. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. These are seashells, the shells of various marine mollusks including both gastropod and bivalves. These are holoplanktonic opisthobranch gastropod mollusks in the informal group Opisthobranchia. The veliger is the characteristic larva of the gastropod, bivalve and scaphopod taxonomic classes. Their diets include clams and oysters, arthropods, small fish and gastropod molluscs. Hermaphroditic gastropod snails mate using love darts. One example of asymmetric invertebrates includes all gastropod species. "L. littorea" is an omnivorous, grazing intertidal gastropod. The larval shell of a gastropod is called a protoconch. Sclerites are not homologous to a gastropod operculum. The radula of a gastropod is usually adapted to the food that a species eats. The streptaxid "Careoradula perelegans" is the only known terrestrial gastropod which has no radula.