Freshwater molluscs include freshwater snails and freshwater bivalves. Fossil invertebrates include freshwater snails and clams. Predatory leeches feed on small invertebrates such as snails, earthworms and insect larvae. Hatchlings mostly feed on invertebrates such as insects, insect larvae, snails, spiders, and worms. The bacterial mats provide nourishment for mussels, clams, limpets and sea snails. The UP also contains many shellfish, such as clams, aquatic snails, and crayfish. It occasionally feeds on arboreal insects, snails, and small salamanders. Shells of bivalves and aquatic snails are also common. Openbills are specialists in freshwater molluscs, particularly apple snails. Rarely, they will eat snails or insects. It eats berries, nuts, insects, small fruit, snails, and seeds. Gastropods such as snails and slugs also cause damage to growth. These parasites are released from infected freshwater snails. The shells of most species of sea snails are spirally coiled. They are seen feeding heavily on bugs, snails and foliage.