Larva


(Redirected from Larvae)

A larva /ˈlɑːrvə/ (plural larvae /ˈlɑːrv/) 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 environments separate from 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 immobile but their larvae are mobile, and use their mobile larval form to distribute themselves.[1][2]

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]

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 the larval form may differ more than the adult form from the group's common origin.[7]

Contents

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 Turbellaria: Müller's larva, Götte’s larva;
Trematoda: miracidium, sporocyst, redia, cercaria;
Monogenea: oncomiracidium;
Cestoda: cysticercus, cysticercoid, oncosphere (or hexacanth), coracidium, plerocercoid
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 molluscs, annelids, nemerteans and sipunculids trochophore
Certain molluscs veliger
Mollusca: freshwater Bivalvia (mussels) glochidium
Arthropoda: †Trilobita protaspis (unjointed), meraspis (increasing number of joints, but 1 less than the holaspis), holaspis (=adult)[8]
Arthropoda: Xiphosura euproöps larva ("trilobite larva")
Arthropoda: Pycnogonida protonymphon
Crustaceans General: nauplius, metanauplius, protozoea, antizoea, pseudozoea, zoea, postlarva, cypris, primary larva, mysis
Decapoda: zoea
Rhizocephala: 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
Fish: Petromyzontiformes (lamprey) ammocoete
Fish: Anguilliformes (eels) leptocephalus
Amphibians tadpole, polliwog

Insect larvae


Within Insects, only 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]

  1. Apodous larvae – no legs at all and are poorly sclerotized. Based on sclerotization, three apodous forms are recognized.
  2. Protopod larvae – larva have many different forms and often unlike a normal insect form. They hatch from eggs which contains very little yolk. E.g. first instar larvae of parasitic hymenoptera.
  3. Polypod larvae – also known as eruciform larvae, these larva have abdominal prolegs, in addition to usual thoracic legs. They poorly sclerotized and relatively inactive. They live in close contact with the 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. ^ Qian, Pei-Yuan (1999), "Larval settlement of polychaetes", Reproductive Strategies and Developmental Patterns in Annelids, Dordrecht: Springer Netherlands, pp. 239–253, doi:10.1007/978-94-017-2887-4_14 , ISBN 978-90-481-5340-4
  2. ^ Chen, Zhang-Fan; Zhang, Huoming; Wang, Hao; Matsumura, Kiyotaka; Wong, Yue Him; Ravasi, Timothy; Qian, Pei-Yuan (2014-02-13). "Quantitative Proteomics Study of Larval Settlement in the Barnacle Balanus amphitrite" . PLOS ONE. 9 (2): e88744. doi:10.1371/journal.pone.0088744 . ISSN 1932-6203 . PMID 24551147 .
  3. ^ Sen, R; Gadagkar, R (2006). "Males of the social wasp Ropalidia marginata can feed larvae, given an opportunity". Animal Behaviour. 71 (2): 345–350. doi:10.1016/j.anbehav.2005.04.022 . S2CID 39848913 .
  4. ^ Wakahara, Masami (1996). "Heterochrony and Neotenic Salamanders: Possible Clues for Understanding the Animal Development and Evolution". Zoological Science. 13 (6): 765–776. doi:10.2108/zsj.13.765 . ISSN 0289-0003 . PMID 9107136 . S2CID 35101681 .
  5. ^ Nagy, Lisa M.; Grbić, Miodrag (1999), "Cell Lineages in Larval Development and Evolution of Holometabolous Insects", The Origin and Evolution of Larval Forms, Elsevier, pp. 275–300, doi:10.1016/b978-012730935-4/50010-9 , ISBN 978-0-12-730935-4
  6. ^ Raff, Rudolf A (2008-01-11). "Origins of the other metazoan body plans: the evolution of larval forms" . Philosophical Transactions of the Royal Society B: Biological Sciences. 363 (1496): 1473–1479. doi:10.1098/rstb.2007.2237 . ISSN 0962-8436 . PMC 2614227 . PMID 18192188 .
  7. ^ Williamson, Donald I. (2006). "Hybridization in the evolution of animal form and life-cycle" . Zoological Journal of the Linnean Society. 148 (4): 585–602. doi:10.1111/j.1096-3642.2006.00236.x .
  8. ^ Moore, R.C. (1959). Arthropoda I – Arthropoda General Features, Proarthropoda, Euarthropoda General Features, Trilobitomorpha. Treatise on Invertebrate Paleontology. Part O. Boulder, Colorado/Lawrence, Kansas: Geological Society of America/University of Kansas Press. pp. O121, O122, O125. ISBN 978-0-8137-3015-8.
  9. ^ "Division: Endopterygota - Amateur Entomologists' Society (AES)" . www.amentsoc.org. Retrieved 2020-08-03.
  10. ^ "Recognizing Insect Larval Types" . University of Kentucky. Retrieved 28 April 2016.
  11. ^ JOHNSON, NORMAN. TRIPLEHORN, CHARLES A. (2020). BORROR AND DELONG'S INTRODUCTION TO THE STUDY OF INSECTS. CENGAGE LEARNING CUSTOM P. ISBN 978-0-357-67127-6. OCLC 1163940863 .CS1 maint: multiple names: authors list (link)
  12. ^ Capinera, John L., ed. (2008). Encyclopedia of Entomology. Dordrecht: Springer Netherlands. doi:10.1007/978-1-4020-6359-6 . ISBN 978-1-4020-6242-1.
  13. ^ "Types of Insect Larva" . Agri info. Archived from the original on 14 May 2016. Retrieved 28 April 2016.

External links


Bibliography









Categories: Larvae | Insect developmental biology




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