Larva  

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-:''[[host (biology)]]''+A '''larva''' ([[Latin]]; plural ''larvae'') is a distinct juvenile form many [[animals]] undergo before [[metamorphosis]] into adults. Animals with indirect [[developmental biology|development]] such as [[insect]]s, [[amphibians]], or [[cnidarians]] typically have a larval phase of their life cycle.
-''[[Dicrocoelium dendriticum]]'' spends its adult [[Biological life cycle|life]] inside the [[liver]] of its [[host (biology)|host]]. After mating, the eggs are excreted in the [[feces]].+The larva's appearance is generally very different from the adult form (''eg.'' [[caterpillar]]s and [[butterfly|butterflies]]), and a larva can often have unique structures and ''larval'' organs that do not occur in the adult form. A larva's diet can be considerably different from its adult form.
-The first [[intermediate host]], the terrestrial [[snail]] (''Cionella lubrica'' in the United States), eats the feces, and becomes infected by the [[larva]]l parasites. The larvae (or [[Miracidium|cercariae]]) drill through the wall of the gut and settle in its digestive tract, where they develop into a juvenile stage. The snail tries to defend itself by walling the parasites off in cysts, which it then excretes and leaves behind in the grass.+Larvae are frequently adapted to environments separate from adults. For example, some larvae such as [[tadpoles]] live exclusively in aquatic environments, but as adults can live outside water as [[frogs]]. By living in distinct environments, larvae may be given shelter from predators and reduce competition for resources with the adult population.
-The second intermediate host, an [[ant]] (''[[Formica fusca]]'' in the United States), uses the trail of slime as a source of moisture. The [[ant]] then swallows a cyst loaded with hundreds of juvenile lancet flukes. The parasites enter the gut and then drift through its body. Most of the cercariae encyst in the haemocoel of the ant and mature into [[Miracidium|metacercariae]], but one moves to the sub-esophageal [[ganglion]] (a cluster of [[nerve cell]]s underneath the [[esophagus]]). Infected ants may contain 100 metacercariae, and a high percentage of ants may be infected. Typical infections in cattle may be in the tens of thousands of adult worms. There, the fluke takes control of the ant's actions by manipulating these nerves. As evening approaches and the air cools, the infested ant is drawn away from other members of the colony and upward to the top of a blade of grass. Once there, it clamps its [[mandible (arthropod)|mandible]]s onto the top of the blade and stays there until dawn. Afterward, it goes back to its normal activity at the ant colony. If the host ant were to be subjected to the heat of the direct sun, it would die along with the parasite. Night after night, the ant goes back to the top of a blade of grass until a grazing animal comes along and eats the blade, ingesting the ant along with it, thus putting lancet flukes back inside their host.+Animals in the larval stage animals will consume food to fuel their transition into the adult form. Some species such as [[barnacles]] are immobile as adults, and use their mobile larvae form to distribute themselves.
-They live out their adult lives inside the animal, reproducing so that the cycle begins again.+The larvae of some species can become [[puberty|pubescent]] and not further develop into the adult form (for example, in some [[newt]]s). This is a type of [[neoteny]].
 + 
 +It is a misunderstanding that the larval form always [[ontogeny recapitulates phylogeny|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.
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A larva (Latin; 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 (eg. caterpillars and butterflies), and a larva can often have unique structures and larval organs that do not occur in the adult form. A larva's diet can be considerably different from its adult form.

Larvae are frequently adapted to environments separate from adults. For example, some larvae such as tadpoles live exclusively in aquatic environments, but as adults can live outside water as frogs. By living in distinct environments, larvae may be given shelter from predators and reduce competition for resources with the adult population.

Animals in the larval stage animals will consume food to fuel their transition into the adult form. Some species such as barnacles are immobile as adults, and use their mobile larvae form to distribute themselves.

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.




Unless indicated otherwise, the text in this article is either based on Wikipedia article "Larva" or another language Wikipedia page thereof used under the terms of the GNU Free Documentation License; or on research by Jahsonic and friends. See Art and Popular Culture's copyright notice.

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