Larva
A larva (/ˈlɑːrvə/; pl.: larvae /ˈlɑːrviː/) 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
Animals in the larval stage will consume food to fuel their transition into the adult form. In some organisms like
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[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 |
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 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
Within
- Apodous larvae – no legs at all and are poorly sclerotized. Based on apodousforms are recognized.
- Eucephalous – with well sclerotized head capsule. Found in Cerambycidaefamilies.
- Hemicephalus – with a reduced head capsule, retractable in to the thorax. Found in Tipulidae and Brachycera families.
- Acephalus – without head capsule. Found in Cyclorrhapha
- Eucephalous – with well sclerotized head capsule. Found in
- 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.
- 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.
- 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
- Crustacean larvae
- Ichthyoplankton
- Maggots
- Spawn (biology)
- Non-larval animal juvenile (immature) stages and other life cycle stages:
- In Porifera: olynthus, gemmule
- In medusa
- In cephalopods
- In hydatid cyst
- In Bryozoa: avicularium
- In Acanthocephala: cystacanth
- In Insecta:
- Nymphs and naiads, immature forms in hemimetabolous insects
- Ephemeroptera
- Instar, intermediate between each ecdysis
- chrysalis, intermediate stages between larva and imago(the adult stage)
- In
- Protozoan life cycle stages
- Algal life cycle stages:
- Codiolum-phase
- Conchocelis-phase
- Marine larval ecology
References
- ISBN 978-90-481-5340-4
- PMID 24551147.
- S2CID 39848913.
- S2CID 35101681.
- ISBN 978-0-12-730935-4
- PMID 18192188.
- .
- ISBN 978-0-8137-3015-8.
- ^ "Division: Endopterygota – Amateur Entomologists' Society (AES)". www.amentsoc.org. Retrieved 2020-08-03.
- ^ "Recognizing Insect Larval Types". University of Kentucky. Retrieved 28 April 2016.
- OCLC 1163940863.)
{{cite book}}
: CS1 maint: multiple names: authors list (link - ISBN 978-1-4020-6242-1.
- ^ "Types of Insect Larva". Agri info. Archived from the original on 14 May 2016. Retrieved 28 April 2016.
- ^ "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.