Among vertebrates a number of fishes pass through larval stages; the larva of the eel is interesting because it is flat and transparent. The tadpole, the familiar larva of the amphibian, develops to a considerable size in the relatively hospitable aquatic environment before metamorphosis prepares it for an amphibious or terrestrial life as a frog or toad.
In some animals, especially insects, larvae represent a special feeding stage in the life cycle. Some insects pass through more or less wormlike larval stages, enter the outwardly inactive, or pupal, form, and emerge from the pupal case as adults (see pupa). The importance of larvae in the life cycle of insects varies greatly, as does the proportion of the life span spent in larval, pupal, and adult stages. In many insects, the adult life is relatively short, consisting mostly of mating and egg laying, while the larvae live for many months or, in some species, for several years. Insect larvae feed voraciously, necessarily becoming larger than the adult, as considerable energy and material are needed for the profound changes made during pupation. For this reason, insect larvae often cause far more damage to stored crops and textiles than adult insects.
Insect larvae generally have a thinner exoskeleton than the adult; many are white and soft. The characteristic fly larvae are maggots, often developing in decaying plant or animal material. Mosquito larvae are the familiar aquatic wrigglers; they breathe air and are killed by a thin film of oil on the water that prevents contact with air. Maggots and wrigglers are legless, as are all larvae of the insect order Diptera. Beetle larvae, including the whitish forms called grubs and the long brownish wireworms, are quite diverse, but all are equipped with the six legs characteristic of adults. Moths and butterflies have wormlike caterpillars as larvae, each equipped with the six legs characteristic of adults and false legs known as prolegs to support the long abdominal section. Some, like the milkweed worm (the larva of the monarch butterfly), are relatively naked, while other caterpillars are covered by hairy bristles, sometimes equipped with irritating chemicals that can cause intense itching. The young of the social insects (bees, ants, wasps, and termites) are legless but otherwise grublike. Although all social-insect larvae are ultimately dependent on the parent colony for food, they are considered true larvae because they pass through a pupal stage.
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. Seealso metamorphosis, pupa.
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The larva can look completely different from the adult form, for example, a caterpillar differs from a butterfly. Larvae often have special (larval) organs which do not occur in the adult form. The larvae of some species can become pubescent and not further develop into the adult form (for example, in some newts). This is a type of neoteny.
It is a misunderstanding that the larval form always reflects the group's evolutionary history. It could be the case, but often the larval stage has evolved secondarily, as in insects. In these cases the larval form might differ more from the group's common origin than the adult form.
The early life stages of most fish species are considerably different from juveniles and adults of their species and are called larvae.
Names of various kinds of larvae:
|Animal||Name of larva|
|Mayflies, Grasshoppers, True Bugs, etc.||nymph|
|Dragonflies, Damselflies||naiad, nymph|
|Butterflies and moths||caterpillar|
|Beetles, Bees, Wasps||grub|
|Certain molluscs, annelids||trochophore|
Mature larvae of Hydroporus signatus Sharp (Coleoptera: Dytiscidae) as substrates for Peritrichida.(SHORTER COMMUNICATION)(Report)
Dec 22, 2007; ABSTRACT Mature Larvae of Hydroporus signatus Sharp collected from a small eutrophic habitat served as substrates for...