Larva

Last updated
Larva of the Papilio xuthus butterfly Papilio xuthus Larva 2011-10-15.jpg
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.

Contents

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 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] 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 Eurosta solidaginis larva.jpg
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

AnimalName 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

The larvae of the Hercules beetle (Dynastes hercules) are among the largest of any species of insect Hercules beetle (larva).jpg
The larvae of the Hercules beetle (Dynastes hercules) are among the largest of any species of insect
Campodeiform larva of Micromus sp. Micromus.aphids.2.jpg
Campodeiform larva of Micromus sp.

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] [14]

  1. Apodous larvae – no legs at all and are poorly sclerotized. Based on sclerotization. All Apocrita are apodous. 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 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

Related Research Articles

<span class="mw-page-title-main">Metamorphosis</span> Profound change in body structure during the postembryonic development of an organism

Metamorphosis is a biological process by which an animal physically develops including birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some insects, jellyfish, fish, amphibians, mollusks, crustaceans, cnidarians, echinoderms, and tunicates undergo metamorphosis, which is often accompanied by a change of nutrition source or behavior. Animals can be divided into species that undergo complete metamorphosis ("holometaboly"), incomplete metamorphosis ("hemimetaboly"), or no metamorphosis ("ametaboly").

<span class="mw-page-title-main">Echinoderm</span> Exclusively marine phylum of animals with generally 5-point radial symmetry

An echinoderm is any member of the phylum Echinodermata. The adults are recognisable by their radial symmetry, or pentamerous symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Adult echinoderms are found on the sea bed at every ocean depth, from the intertidal zone to the abyssal zone. The phylum contains about 7,000 living species, making it the second-largest grouping of deuterostomes, after the chordates. Echinoderms are the largest entirely marine phylum. The first definitive echinoderms appeared near the start of the Cambrian.

<span class="mw-page-title-main">Lepidoptera</span> Order of insects including moths and butterflies

Lepidoptera or lepidopterans is an order of winged insects that includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organisms, making it the second largest insect order with 126 families and 46 superfamilies. and one of the most widespread and widely recognizable insect orders in the world.

<span class="mw-page-title-main">Silphidae</span> Family of beetles

Silphidae is a family of beetles that are known commonly as large carrion beetles, carrion beetles or burying beetles. There are two subfamilies: Silphinae and Nicrophorinae. Nicrophorines are sometimes known as sexton beetles. The number of species is relatively small at around two hundred. They are more diverse in the temperate region although a few tropical endemics are known. Both subfamilies feed on decaying organic matter such as dead animals. The subfamilies differ in which uses parental care and which types of carcasses they prefer. Silphidae are considered to be of importance to forensic entomologists because when they are found on a decaying body they are used to help estimate a post-mortem interval.

<span class="mw-page-title-main">Pupa</span> Life stage of some insects undergoing transformation

A pupa is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their life cycle, the stages thereof being egg, larva, pupa, and imago. The processes of entering and completing the pupal stage are controlled by the insect's hormones, especially juvenile hormone, prothoracicotropic hormone, and ecdysone. The act of becoming a pupa is called pupation, and the act of emerging from the pupal case is called eclosion or emergence.

<span class="mw-page-title-main">Sawfly</span> Suborder of insects

Sawflies are wasp-like insects that are in the suborder Symphyta within the order Hymenoptera, alongside ants, bees, and wasps. The common name comes from the saw-like appearance of the ovipositor, which the females use to cut into the plants where they lay their eggs. The name is associated especially with the Tenthredinoidea, by far the largest superfamily in the suborder, with about 7,000 known species; in the entire suborder, there are 8,000 described species in more than 800 genera. Symphyta is paraphyletic, consisting of several basal groups within the order Hymenoptera, each one rooted inside the previous group, ending with the Apocrita which are not sawflies.

<span class="mw-page-title-main">Histeridae</span> Family of beetles

Histeridae is a family of beetles commonly known as clown beetles or hister beetles. This very diverse group of beetles contains 3,900 species found worldwide. They can be easily identified by their shortened elytra that leaves two of the seven tergites exposed, and their geniculate (elbowed) antennae with clubbed ends. These predatory feeders are most active at night and will fake death if they feel threatened. This family of beetles will occupy almost any kind of niche throughout the world. Hister beetles have proved useful during forensic investigations to help in time of death estimation. Also, certain species are used in the control of livestock pests that infest dung and to control houseflies. Because they are predacious and will even eat other hister beetles, they must be isolated when collected.

<span class="mw-page-title-main">Caddisfly</span> Order of caddisflies

The caddisflies, or order Trichoptera, are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the basis of the adult mouthparts. Integripalpian larvae construct a portable casing to protect themselves as they move around looking for food, while annulipalpian larvae make themselves a fixed retreat in which they remain, waiting for food to come to them. The affinities of the small third suborder Spicipalpia are unclear, and molecular analysis suggests it may not be monophyletic. Also called sedge-flies or rail-flies, the adults are small moth-like insects with two pairs of hairy membranous wings. They are closely related to the Lepidoptera which have scales on their wings; the two orders together form the superorder Amphiesmenoptera.

<span class="mw-page-title-main">Veliger</span> Larval stage of some snails

A veliger is the planktonic larva of many kinds of sea snails and freshwater snails, as well as most bivalve molluscs (clams) and tusk shells.

Holometabolism, also called complete metamorphosis, is a form of insect development which includes four life stages: egg, larva, pupa, and imago. Holometabolism is a synapomorphic trait of all insects in the superorder Holometabola. Immature stages of holometabolous insects are very different from the mature stage. In some species the holometabolous life cycle prevents larvae from competing with adults because they inhabit different ecological niches. The morphology and behavior of each stage are adapted for different activities. For example, larval traits maximize feeding, growth, and development, while adult traits enable dispersal, mating, and egg laying. Some species of holometabolous insects protect and feed their offspring. Other insect developmental strategies include ametabolism and hemimetabolism.

<span class="mw-page-title-main">Phoridae</span> Family of flies

The Phoridae are a family of small, hump-backed flies resembling fruit flies. Phorid flies can often be identified by their escape habit of running rapidly across a surface rather than taking to the wing. This behaviour is a source of one of their alternate names, scuttle fly. Another vernacular name, coffin fly, refers to Conicera tibialis. About 4,000 species are known in 230 genera. The most well-known species is cosmopolitan Megaselia scalaris. At 0.4 mm in length, the world's smallest fly is the phorid Euryplatea nanaknihali.

<i>Arachnocampa</i> Genus of flies

Arachnocampa is a genus of nine fungus gnat species which have a bioluminescent larval stage, akin to the larval stage of glowworm beetles. The species of Arachnocampa are endemic to Australia and New Zealand, dwelling in caves and grottos, or sheltered places in forests.

<span class="mw-page-title-main">Ceratopogonidae</span> Family of flies commonly known as no see ums, or biting midges

Ceratopogonidae is a family of flies commonly known as no-see-ums, or biting midges, generally 1–3 millimetres in length. The family includes more than 5,000 species, distributed worldwide, apart from the Antarctic and the Arctic.

<span class="mw-page-title-main">Stratiomyidae</span> Family of flies

The soldier flies are a family of flies. The family contains over 2,700 species in over 380 extant genera worldwide. Larvae are found in a wide array of locations, mostly in wetlands, damp places in soil, sod, under bark, in animal excrement, and in decaying organic matter. Adults are found near larval habitats. They are diverse in size and shape, though they commonly are partly or wholly metallic green, or somewhat wasplike mimics, marked with black and yellow or green and sometimes metallic. They are often rather inactive flies which typically rest with their wings placed one above the other over the abdomen.

The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments are of Latin origin, and may be confused with terms for bones: coxa, trochanter, femur, tibia, tarsus, ischium, metatarsus, carpus, dactylus, patella.

<span class="mw-page-title-main">Planidium</span>

A planidium is a specialized form of insect larva seen in the first-instar of a few families of insects that have parasitoidal ways of life. They are usually flattened, highly sclerotized (hardened), and quite mobile. The function of the planidial stage is to find a host on which the later larval instars may feed, generally until the insect pupates.

Marine larval ecology is the study of the factors influencing dispersing larvae, which many marine invertebrates and fishes have. Marine animals with a larva typically release many larvae into the water column, where the larvae develop before metamorphosing into adults.

<span class="mw-page-title-main">External morphology of Lepidoptera</span> External features of butterflies and moths

The external morphology of Lepidoptera is the physiological structure of the bodies of insects belonging to the order Lepidoptera, also known as butterflies and moths. Lepidoptera are distinguished from other orders by the presence of scales on the external parts of the body and appendages, especially the wings. Butterflies and moths vary in size from microlepidoptera only a few millimetres long, to a wingspan of many inches such as the Atlas moth. Comprising over 160,000 described species, the Lepidoptera possess variations of the basic body structure which has evolved to gain advantages in adaptation and distribution.

<span class="mw-page-title-main">Crustacean larva</span> Crustacean larval and immature stages between hatching and adult form

Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow. The larvae of crustaceans often bear little resemblance to the adult, and there are still cases where it is not known what larvae will grow into what adults. This is especially true of crustaceans which live as benthic adults, more-so than where the larvae are planktonic, and thereby easily caught.

<i>Chironomus zealandicus</i> Species of midge

Chironomus zealandicus, commonly known as the New Zealand midge, common midge, or non-biting midge, is an insect of the Chironomidae family that is endemic to New Zealand. The worm-like larvae are known to fisherman and have a common name of blood worm due to their red color and elongated blood gills.

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. Bibcode:2014PLoSO...988744C. doi: 10.1371/journal.pone.0088744 . ISSN   1932-6203. PMC   3923807 . 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. Vol. 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.{{cite book}}: 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.
  14. "Types of Insect Larva". agriinfo.in. 2017-03-23. Retrieved 2021-11-22.

Bibliography