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Larva

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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). A larva often has unique structures and organs that do not occur in the adult form, while their diet might be considerably different.

Larvae are frequently adapted to environments separate from adults. For example, some larvae such as tadpoles live 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 species like barnacles, adults are immobile but their larvae are mobile, and use their mobile larval form to distribute themselves.

Some larvae are dependent on adults to feed them. In many eusocial Hymenoptera species, the larvae are fed by female workers. In R. marginata the males are also capable of feeding larvae but they are much less efficient, spending more time and getting less food to the larvae. [1]

The larvae of some species (for example, some newts) can become pubescent and do not develop further into the adult form. This is a type of neoteny.

Eurosta solidaginis Goldenrod Gall Fly larva

It is a misunderstanding that the larval form always reflects the group's evolutionary history. This could be the case, but often the larval stage has evolved secondarily, as in insects. In these cases the larval form may differ more than the adult form from the group's common origin.

Selected types of larvae

Animal Name of larva
Cnidarians planula, actinula
Crustacea: Decapoda zoea
Insecta: Lepidoptera (butterflies and moths) caterpillar
Insecta: Beetles grub
Insecta: Flies, Bees, Wasps maggot
Insecta: Mosquitoes wriggler
Certain molluscs, annelids, nemerteans and sipunculids trochophore
Certain molluscs veliger
Mollusca: freshwater Bivalvia (mussels) glochidium
Petromyzontiformes (lamprey) ammocoete
Fish (generally) larva
Fish: Anguilliformes (eels) leptocephalus
Amphibians tadpole, polliwog
Phoronids actinotroch
Porifera (sponges) coeloblastula larvae (= blastula larvae), parenchymula (= parenchymella), amphiblastula
Cycliophora pandora, chordoid larva
Nemertea pilidium, Iwata larva, Desor larva
Hemichordata tornaria
Acanthocephala acanthor
Ctenophora cydippid larvae
Deuterostomes dipleurula (hypothetical larva)
Arthropoda: Xiphosura euproöps larva ("trilobite larva")
Platyhelminthes Götte’s larva, Müller's larva, miracidium, oncomiracidium, coracidium
Locifera Higgins larva
Dicyemida infusoriform larva
Brachiopoda lobate larva
Priapula loricate larva
Crustaceans nauplius, metanauplius, protozoea, antizoea, pseudozoea, zoea, postlarva, cypris, primary larva, mysis
Arthropoda: †Trilobita protaspis (unjointed), meraspis (increasing number of joints, but 1 less than the holaspis), holaspis (=adult)[2]
Arthropoda: Pycnogonida protonymphon
Urochordata tadpole (does not feed, technically a "swimming embryo")
Echinodermata bipinnaria, vitellaria, brachiollaria, pluteus, ophiopluteus, echinopluteus, auricularia
Nematomorpha nematomorphan larva
Sipuncula pelagosphera larva
Annelida nectochaeta, polytroch
Ectoprocta cyphonautes, vesiculariform larvae
Heterocyemida Wagener's larva
Nematoda Dauer larva

See also

References

  1. ^ Sen, R; Gadagkar, R (2006). "Males of the social wasp Ropalidia marginata can feed larvae, given an opportunity". Animal Behavior 71: 345-350. 
  2. ^ Moore, R.C. (1959). Arthropoda I - Arthropoda General Features, Proarthropoda, Euarthropoda General Features, Trilobitomorpha.  

External links

  • Media related to at Wikimedia Commons
  • The dictionary definition of at Wiktionary
  • Arenas-Mena, C. (2010) Indirect development, transdifferentiation and the macroregulatory evolution of metazoans. Philosophical Transactions of the Royal Society B: Biological Sciences. Feb 27, 2010 Vol.365 no.1540 653-669

Bibliography

  • Brusca, R. C., & Brusca, G. J. (2003). Invertebrates (2nd ed.). Sunderland, Mass. : Sinauer Associates.
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