larva(redirected from cutaneous larva migrans)
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larva,independent, immature animal that undergoes a profound change, or metamorphosis, to assume the typical adult form. Larvae occur in almost all of the animal phyla; because most are tiny or microscopic, they are rarely seen. They play diverse roles in the lives of animals. Motile larvae help to disseminate sessile, or sedentary, animals such as spongessponge,
common name for members of the aquatic animal phylum Porifera, and for the dried, processed skeletons of certain species used to hold water. Over 4,500 living species are known; they are found throughout the world, especially in shallow temperate waters.
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bivalve mollusk found in beds in shallow, warm waters of all oceans. The shell is made up of two valves, the upper one flat and the lower convex, with variable outlines and a rough outer surface.
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common name of the sedentary crustacean animals constituting the infraclass Cirripedia. Barnacles are exclusively marine and are quite unlike any other crustacean because of the permanently attached, or sessile, mode of existence for which they are highly modified.
..... Click the link for more information. , or scale insects. Larvae of parasites may be dispersed by penetrating the skin of new hosts; other parasite larvae live in intermediate hosts that are normally eaten by the final host, in which the adult parasites develop. The larvae of other parasites live in and are dispersed by intermediate hosts such as mosquitoesmosquito
, small, long-legged insect of the order Diptera, the true flies. The females of most species have piercing and sucking mouth parts and apparently they must feed at least once upon mammalian blood before their eggs can develop properly.
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common name for any one of a number of small, fragile-looking two-winged flies of the suborder Nematocera, order Diptera, which includes the families Tipulidae (crane flies), Bibionidae (hairflies), Ceratopogonidae (biting midges), Chironomidae (true midges), Cecidomyidae
..... Click the link for more information. , or leechesleech,
predacious or parasitic annelid worm of the class Hirudinea, characterized by a cylindrical or slightly flattened body with suckers at either end for attaching to prey.
..... Click the link for more information. ; when the blood meals are taken from the final host, the parasite larvae are introduced into the blood or skin. Parasitic infections can often be reduced by eliminating the larval hosts.
any animal having a backbone or spinal column. Verbrates can be traced back to the Silurian period. In the adults of nearly all forms the backbone consists of a series of vertebrae. All vertebrates belong to the subphylum Vertebrata of the phylum Chordata.
..... Click the link for more information. a number of fishesfish,
limbless aquatic vertebrate animal with fins and internal gills. Traditionally the living fish have been divided into three class: the primitive jawless fishes, or Agnatha; the cartilaginous (sharklike) fishes, or Chondrichthyes; and the bony fishes, or Osteichthyes.
..... Click the link for more information. pass through larval stages; the larva of the eeleel,
common name for any fish in the order Anguilliformes, and characterized by a long snakelike body covered with minute scales embedded in the skin. Eels lack the hind pair of fins, adapting them for wriggling in the mud and through the crevices of reefs and rocky shores.
..... Click the link for more information. is interesting because it is flat and transparent. The tadpole, the familiar larva of the amphibianamphibian,
in zoology, cold-blooded vertebrate animal of the class Amphibia. There are three living orders of amphibians: the frogs and toads (order Anura, or Salientia), the salamanders and newts (order Urodela, or Caudata), and the caecilians, or limbless amphibians (order
..... Click the link for more information. , develops to a considerable size in the relatively hospitable aquatic environment before metamorphosis prepares it for an amphibious or terrestrial life as a frogfrog,
common name for an amphibian of the order Anura. Frogs are found all over the world, except in Antarctica. They require moisture and usually live in quiet freshwater or in the woods. Some frogs are highly aquatic, while others are better adapted to terrestrial habitats.
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name applied to certain members of the amphibian order Anura, which also includes the frog. Although there is no clear-cut distinction between toads and frogs, the name toad
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In some animals, especially insectsinsect,
invertebrate animal of the class Insecta of the phylum Arthropoda. Like other arthropods, an insect has a hard outer covering, or exoskeleton, a segmented body, and jointed legs. Adult insects typically have wings and are the only flying invertebrates.
..... Click the link for more information. , 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 pupapupa
, name for the third stage in the life of an insect that undergoes complete metamorphosis, i.e., develops from the egg through the larva and the pupa stages to the adult.
..... Click the link for more information. ). 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 flyfly,
name commonly used for any of a variety of winged insects, but properly restricted to members of the order Diptera, the true flies, which includes the housefly, gnat, midge, mosquito, and tsetse fly.
..... Click the link for more information. 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. Beetlebeetle,
common name for insects of the order Coleoptera, which, with more than 300,000 described species, is the largest of the insect orders. Beetles have chewing mouthparts and well-developed antennae.
..... Click the link for more information. larvae, including the whitish forms called grubs and the long brownish wirewormswireworm,
elongate, cylindrical larva of the click beetle. Most wireworms are hard and brown, but members of some species are soft and whitish. Wireworms live in rotten wood or in the ground and feed on roots and seeds, injuring potatoes, grasses, and a wide variety of
..... Click the link for more information. , are quite diverse, but all are equipped with the six legs characteristic of adults. Mothsmoth,
any of the large and varied group of insects which, along with the butterflies, make up the order Lepidoptera. The moths comprise the great majority of the 100,000 species of the order, and about 70 of its 80 families.
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any of a large group of insects found throughout most of the world; with the moths, they comprise the order Lepidoptera. There are about 12 families of butterflies. Most adult moths and butterflies feed on nectar sucked from flowers.
..... Click the link for more information. 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 (beesbee,
name for flying insects of the superfamily Apoidea, in the same order as the ants and the wasps. Bees are characterized by their enlarged hind feet, typically equipped with pollen baskets of stiff hairs for gathering pollen.
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any of the 2,500 insect species constituting the family Formicidae of the order Hymenoptera, to which the bee and the wasp also belong. Like most members of the order, ants have a "wasp waist," that is, the front part of the abdomen forms a narrow stalk, called the waist,
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name applied to many winged insects of the order Hymenoptera, which also includes ants and bees. Most wasps are carnivorous, feeding on insects, grubs, or spiders. They have biting mouthparts, and the females have stings with which they paralyze their prey.
..... Click the link for more information. , and termitestermite
or white ant,
common name for a soft-bodied social insect of the infraorder Isoptera. Originally classified in as a separate order, termites are genetically related to cockroaches and are now usually classified with them in the order Blattodea.
..... Click the link for more information. ) 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.
a stage in the individual development of many invertebrates and some vertebrates (fishes and amphibians) in which the nutrient reserves of the egg are insufficient to complete embryonic development.
An organism in the larval stage is self-sufficient. Usually it has special organs not characteristic of the adult form but lacks other organs characteristic of the adult. In many animals, the existence of the larval stage is determined by the differences in the modes of life of the early stages of development and that of the adult stage; thus, the trochophore, characteristic of polychaetes and many mollusks, is free-swimming, but the adult form is benthic. The presence of a larva is sometimes associated with a change in habitat in the course of development. For example, many amphibian larvae are adapted to aquatic life, whereas the adult animals are adapted to dry land. In sessile or sluggish marine animals, a free-swimming larva ensures offspring distribution. This is true of the larvae of sponges and coelenterates (paren-chymula, amphiblastula, planula) and of echinoderms and enteropneusts (dipleurula).
The metamorphosis of the larva to the adult animal consists in the restructuring of the larva’s organization; the more profound that restructuring, the greater will be the difference between the larva and the adult organism. The changes that occur in the metamorphosis of certain invertebrates (nemertines, echinoderms, and insects) are especially pronounced. For example, in higher insects in the pupal stage (which follows the larval stage), almost all of the larval organs are destroyed. The organs of the adult animal are formed de novo from special rudiments called imaginal disks. The larvae of some animals retain the structural characteristics of ancestral forms. For example, phylogenetic significance of this sort is ascribed to the larvae of sponges and coelenterates (parenchymula, planula) and to the caudate larvae of ascidians, which resemble a free-swimming ancestor in structure.
A. V. IVANOV