Active, feeding stage in the development of many animals, occurring after birth or hatching and before the adult form is reached. Larvae are structurally different from adults and often are adapted to a different environment. Some species have free-living larvae but sessile (affixed) adults, the moving larvae thus helping to spread the species; others have aquatic larvae but terrestrial adults. Most larvae are tiny; many are dispersed by entering a host's body, where the adult form of the parasite emerges. Many invertebrates (e.g., cnidarians) have simple larvae. Flukes have several larval stages, and annelids, mollusks, and crustaceans have various larval forms. Insect larvae are called caterpillars, grubs, maggots, or worms; the larval stage of many insects may last much longer than the adult stage (e.g., some cicadas live 17 years as larvae and a week as adults). Echinoderms also have larval forms. The larvae of frogs and toads are called tadpoles. See also metamorphosis, pupa.
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