Larva

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(Redirected from
Nectochaete
)
Larva of the Papilio xuthus butterfly

A larva (/ˈlɑːrvə/; pl.: larvae /ˈlɑːrv/) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.

A 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

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

barnacles, adults are immobile but their larvae are mobile, and use their mobile larval form to distribute themselves.[1][2] These larvae used for dispersal are either planktotrophic (feeding) or lecithotrophic (non-feeding)
.

Some larvae are dependent on adults to feed them. In many eusocial Hymenoptera species, the larvae are fed by female workers. In Ropalidia marginata (a paper wasp) the males are also capable of feeding larvae but they are much less efficient, spending more time and getting less food to the larvae.[3]

The larvae of some organisms (for example, some newts) can become pubescent and do not develop further into the adult form. This is a type of neoteny.[4]

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.[5][6] In these cases[clarification needed], the larval form may differ more than the adult form from the group's common origin.[7]

Selected types of larvae

Animal Name of larvae
Porifera
(sponges)
coeloblastula (= blastula, amphiblastula), parenchymula (= parenchymella, stereogastrula)
Heterocyemida
Wagener's larva
Dicyemida infusoriform larva
Cnidarians
planula (= stereogastrula), actinula
Ctenophora cydippid larvae
Platyhelminthes
Annelida
nectochaete
, polytroch
Nematoda
Dauer larva, microfilaria
Sipuncula pelagosphera larva
Ectoprocta
cyphonautes, vesiculariform larvae
Nematomorpha nematomorphan larva
Phoronids actinotroch
Cycliophora
pandora, chordoid larva
Nemertea pilidium, Iwata larva, Desor larva
Acanthocephala acanthor
Locifera
Higgins larva
Brachiopoda
lobate larva
Priapula
loricate larva
Certain
sipunculids
trochophore
Certain molluscs veliger
Mollusca: freshwater Bivalvia (mussels) glochidium
Trilobita
protaspis (unjointed), meraspis (increasing number of joints, but 1 less than the holaspis), holaspis (=adult)[8]
Arthropoda: Xiphosura
euproöps larva ("trilobite larva")
Pycnogonida
protonymphon
Crustaceans General:
kentrogon
Insecta: Lepidoptera (butterflies and moths) caterpillar
Insecta: Beetles grub
Insecta: Flies, Bees, Wasps maggot
Insecta: Mosquitoes
wriggler
Deuterostomes dipleurula (hypothetical larva)
Echinodermata
bipinnaria, vitellaria, brachiollaria, pluteus, ophiopluteus, echinopluteus, auricularia
Hemichordata
tornaria
Urochordata
tadpole (does not feed, technically a "swimming embryo")
Fish (generally)
Ichthyoplankton
Petromyzontiformes
(lamprey)
ammocoete
Anguilliformes
(eels)
leptocephalus
Amphibians tadpole, polliwog

Insect larvae

The larvae of the Hercules beetle (Dynastes hercules) are among the largest of any species of insect
Campodeiform larva of Micromus sp.

Within

Endopterygotes show complete metamorphosis, including a distinct larval stage.[9][10] Several classifications have been suggested by many entomologists,[11][12] and following classification is based on Antonio Berlese classification in 1913. There are four main types of endopterygote larvae types:[13][14]

  1. Apodous larvae – no legs at all and are poorly sclerotized. Based on
    apodous
    forms are recognized.
  2. Protopod larvae – larva have many different forms and often unlike a normal insect form. They hatch from eggs which contain very little yolk. E.g. first instar larvae of parasitic hymenoptera.
  3. Polypod larvae – also known as eruciform larvae, these larvae have abdominal prolegs, in addition to usual thoracic legs. They are poorly sclerotized and relatively inactive. They live in close contact with their food. Best example is caterpillars of lepidopterans.
  4. Oligopod larvae – have well developed head capsule and mouthparts are similar to the adult, but without compound eyes. They have six legs. No abdominal prolegs. Two types can be seen:
    • Campodeiform – well sclerotized, dorso-ventrally flattened body. Usually long legged predators with prognathous mouthparts. (lacewing, trichopterans, mayflies and some coleopterans).
    • Scarabeiform – poorly sclerotized, flat thorax and abdomen. Usually short legged and inactive burrowing forms. (Scarabaeoidea and other coleopterans).

See also

References

  1. .
  2. .
  3. .
  4. .
  5. .
  6. .
  7. ^ "Division: Endopterygota – Amateur Entomologists' Society (AES)". www.amentsoc.org. Retrieved 2020-08-03.
  8. ^ "Recognizing Insect Larval Types". University of Kentucky. Retrieved 28 April 2016.
  9. OCLC 1163940863.{{cite book}}: CS1 maint: multiple names: authors list (link
    )
  10. .
  11. ^ "Types of Insect Larva". Agri info. Archived from the original on 14 May 2016. Retrieved 28 April 2016.
  12. ^ "Types of Insect Larva". agriinfo.in. 2017-03-23. Retrieved 2021-11-22.

Bibliography

  • Brusca, R. C. & Brusca, G. J. (2003). Invertebrates (2nd ed.). Sunderland, Mass. : Sinauer Associates.
  • Hall, B. K. & Wake, M. H., eds. (1999). The Origin and Evolution of Larval Forms. San Diego: Academic Press.
  • Leis, J. M. & Carson-Ewart, B. M., eds. (2000). The Larvae of Indo-Pacific Coastal Fishes. An Identification Guide to Marine Fish Larvae. Fauna Malesiana handbooks, vol. 2. Brill, Leiden.
  • Minelli, A. (2009). The larva. In: Perspectives in Animal Phylogeny and Evolution. Oxford University Press. p. 160–170. link.
  • Shanks, A. L. (2001). An Identification Guide to the Larval Marine Invertebrates of the Pacific Northwest. Oregon State University Press, Corvallis. 256 pp.
  • Smith, D. & Johnson, K. B. (1977). A Guide to Marine Coastal Plankton and Marine Invertebrate Larvae. Kendall/Hunt Plublishing Company.
  • Stanwell-Smith, D., Hood, A. & Peck, L. S. (1997). A field guide to the pelagic invertebrates larvae of the maritime Antarctic. British Antarctic Survey, Cambridge.
  • Thyssen, P.J. (2010). Keys for Identification of Immature Insects Archived 2017-08-09 at the Wayback Machine. In: Amendt, J. et al. (ed.). Current Concepts in Forensic Entomology, chapter 2, pp. 25–42. Springer: Dordrecht.

External links