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Larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The larva's appearance is generally very different from the adult form (''e.g.'' caterpillars and butterflies) including different unique structures and organs that do not occur in the adult form. Their diet may also be considerably different. Larvae are frequently adapted to different environments than adults. For example, some larvae such as tadpoles live almost exclusively in aquatic environments, but can live outside water as adult frogs. By living in a distinct environment, larvae may be given shelter from predators and reduce competition for resources with the adult population. Animals in the larval stage will consume food to fuel their transition into the adult form. In some organisms like polychaetes and barnacles, adults are immob ...
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Amphibian
Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arboreal or freshwater aquatic ecosystems. Thus amphibians typically start out as larvae living in water, but some species have developed behavioural adaptations to bypass this. The young generally undergo metamorphosis from larva with gills to an adult air-breathing form with lungs. Amphibians use their skin as a secondary respiratory surface and some small terrestrial salamanders and frogs lack lungs and rely entirely on their skin. They are superficially similar to reptiles like lizards but, along with mammals and birds, reptiles are amniotes and do not require water bodies in which to breed. With their complex reproductive needs and permeable skins, amphibians are often ecological indicators; in recent decades there has been a dramatic decli ...
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Caterpillar
Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Symphyta) are commonly called caterpillars as well. Both lepidopteran and symphytan larvae have eruciform body shapes. Caterpillars of most species eat plant material ( often leaves), but not all; some (about 1%) eat insects, and some are even cannibalistic. Some feed on other animal products. For example, clothes moths feed on wool, and horn moths feed on the hooves and horns of dead ungulates. Caterpillars are typically voracious feeders and many of them are among the most serious of agricultural pests. In fact, many moth species are best known in their caterpillar stages because of the damage they cause to fruits and other agricultural produce, whereas the moths are obscure and do no direct harm. Conversely, various species of caterpilla ...
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Tadpoles
A tadpole is the larval stage in the biological life cycle of an amphibian. Most tadpoles are fully aquatic, though some species of amphibians have tadpoles that are terrestrial. Tadpoles have some fish-like features that may not be found in adult amphibians such as a lateral line, gills and swimming tails. As they undergo metamorphosis, they start to develop functional lungs for breathing air, and the diet of tadpoles changes drastically. A few amphibians, such as some members of the frog family Brevicipitidae, undergo direct development i.e., they do not undergo a free-living larval stage as tadpoles instead emerging from eggs as fully formed "froglet" miniatures of the adult morphology. Some other species hatch into tadpoles underneath the skin of the female adult or are kept in a pouch until after metamorphosis. Having no hard skeletons, it might be expected that tadpole fossils would not exist. However, traces of biofilms have been preserved and fossil tadpoles have bee ...
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Newt
A newt is a salamander in the subfamily Pleurodelinae. The terrestrial juvenile phase is called an eft. Unlike other members of the family Salamandridae, newts are semiaquatic, alternating between aquatic and terrestrial habitats. Not all aquatic salamanders are considered newts, however. More than 100 known species of newts are found in North America, Europe, North Africa and Asia. Newts metamorphose through three distinct developmental life stages: aquatic larva, terrestrial juvenile (eft), and adult. Adult newts have lizard-like bodies and return to the water every year to breed, otherwise living in humid, cover-rich land habitats. Newts are threatened by habitat loss, fragmentation and pollution. Several species are endangered, and at least one species, the Yunnan lake newt, has become extinct recently. Etymology The Old English name of the animal was , (of unknown origin), resulting in Middle English ; this word was transformed irregularly into , , or . The initial "n ...
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Metamorphosis
Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some insects, fish, amphibians, mollusks, crustaceans, cnidarians, echinoderms, and tunicates undergo metamorphosis, which is often accompanied by a change of nutrition source or behavior. Animals can be divided into species that undergo complete metamorphosis (" holometaboly"), incomplete metamorphosis ("hemimetaboly"), or no metamorphosis (" ametaboly"). Scientific usage of the term is technically precise, and it is not applied to general aspects of cell growth, including rapid growth spurts. Generally organisms with a larva stage undergo metamorphosis, and during metamorphosis the organism loses larval characteristics. References to "metamorphosis" in mammals are imprecise and only colloquial, but historically idealist ideas of transformation an ...
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Ctenophora
Ctenophora (; ctenophore ; ) comprise a phylum of marine invertebrates, commonly known as comb jellies, that inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming (commonly referred to as "combs"), and they are the largest animals to swim with the help of cilia. Depending on the species, adult ctenophores range from a few millimeters to in size. Only 100 to 150 species have been validated, and possibly another 25 have not been fully described and named. The textbook examples are cydippids with egg-shaped bodies and a pair of retractable tentacles fringed with tentilla ("little tentacles") that are covered with colloblasts, sticky cells that capture prey. Their bodies consist of a mass of jelly, with a layer two cells thick on the outside, and another lining the internal cavity. The phylum has a wide range of body forms, including the egg-shaped cydippids with retractable tentacles that capture prey, the flat generally combless plat ...
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Müller's Larva
Müller's larva or Mulleria is a larva of some Polycladida. It has 8-fold symmetry and is somewhat like a ctenophore. Müller’s larva is ciliated and has several paired and unpaired lobes. The cilia on the lobes are longer than cilia on the rest of the body. At the anterior and posterior ends of the larva are tufts of longer cilia (apical and caudal). The apical tuft originates from the apical organ, a sensory structure associated with the central nervous system. It is named after Johannes Peter Müller Johannes Peter Müller (14 July 1801 – 28 April 1858) was a German physiologist, comparative anatomist, ichthyologist, and herpetologist, known not only for his discoveries but also for his ability to synthesize knowledge. The paramesonephric ... (1801-1858), a German physiologist who invented the plankton net, and first described larval forms of many phyla. References Larvae {{flatworm-stub ...
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Frogs
A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-frog" '' Triadobatrachus'' is known from the Early Triassic of Madagascar, but molecular clock dating suggests their split from other amphibians may extend further back to the Permian, 265 million years ago. Frogs are widely distributed, ranging from the tropics to subarctic regions, but the greatest concentration of species diversity is in tropical rainforest. Frogs account for around 88% of extant amphibian species. They are also one of the five most diverse vertebrate orders. Warty frog species tend to be called toads, but the distinction between frogs and toads is informal, not from taxonomy or evolutionary history. An adult frog has a stout body, protruding eyes, anteriorly-attached tongue, limbs folded underneath, and no tail (the tail of tailed frogs i ...
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Planula
A planula is the free-swimming, flattened, ciliated, bilaterally symmetric larval form of various cnidarian species and also in some species of Ctenophores. Some groups of Nemerteans also produce larvae that are very similar to the planula, which are called planuliform larva. Development The planula forms either from the fertilized egg of a medusa, as is the case in scyphozoans and some hydrozoans, or from a polyp, as in the case of anthozoans. Depending on the species, the planula either metamorphoses directly into a free-swimming, miniature version of the mobile adult form, or navigates through the water until it reaches a hard substrate (many may prefer specific substrates) where it anchors and grows into a polyp. The miniature-adult types include many open-ocean scyphozoans. The attaching types include all anthozoans with a planula stage, many coastal scyphozoans, and some hydrozoans. Feeding and locomotion The planulae of the subphylum Medusozoa have no mouth, and no dig ...
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Barnacles
A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile (nonmobile) and most are suspension feeders, but those in infraclass Rhizocephala are highly specialized parasites on crustaceans. They have four nektonic (active swimming) larval stages. Around 1,000 barnacle species are currently known. The name is Latin, meaning "curl-footed". The study of barnacles is called cirripedology. Description Barnacles are encrusters, attaching themselves temporarily to a hard substrate or a symbiont such as a whale (whale barnacles), a sea snake (''Platylepas ophiophila''), or another crustacean, like a crab or a lobster (Rhizocephala). The most common among them, "acorn barnacles" (Sessilia), are sessile where they grow their shells directly onto the substrate. Pedunculat ...
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Ropalidia Marginata
''Ropalidia marginata'' is an Old World species of paper wasp. It is primitively eusocial, not showing the same bias in brood care seen in other social insects with greater asymmetry in relatedness. The species employs a variety of colony founding strategies, sometimes with single founders and sometimes in groups of variable number. The queen does not use physical dominance to control workers; there is evidence of pheromones being used to suppress other female workers from overtaking queenship. Taxonomy and phylogeny ''R. marginata'' was originally described by Johan Christian Fabricius in 1793 under the name ''Vespa'''' ferruginea'', but that name was previously applied to a different species, so the oldest available name for the species was given by Amédée Louis Michel le Peletier in 1836. One of its subspecies, ''R. marginata jocund'' from New Guinea and Australia, was described in 1898, and two others, ''R. marginata rufitarsis'' from Myanmar and ''R. marginata sundaica'' ...
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Butterfly
Butterflies are insects in the macrolepidopteran clade Rhopalocera from the order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The group comprises the large superfamily Papilionoidea, which contains at least one former group, the skippers (formerly the superfamily "Hesperioidea"), and the most recent analyses suggest it also contains the moth-butterflies (formerly the superfamily "Hedyloidea"). Butterfly fossils date to the Paleocene, about 56 million years ago. Butterflies have a four-stage life cycle, as like most insects they undergo complete metamorphosis. Winged adults lay eggs on the food plant on which their larvae, known as caterpillars, will feed. The caterpillars grow, sometimes very rapidly, and when fully developed, pupate in a chrysalis. When metamorphosis is complete, the pupal skin splits, the adult insect climbs out, and after its wings have expanded and dried, it ...
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