Larva

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Larva of Papilio xuthus, butterfly Papilio xuthus Larva 2011-10-15.jpg
Larva of Papilio xuthus , butterfly

A larva (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.

Contents

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 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 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. [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 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.[ citation needed ] In these cases the larval form may differ more than the adult form from the group's common origin. [2]

Insect larvae

Within Insects, only Endopterygotes show different types of larvae. [3] Several classifications have been suggested by many entomologists, [4] and following classification is based on Antonio Berlese classification in 1913. There are four main types of endopterygote larvae types: [5]

See also

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Caddisfly order of insects

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Planidium

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<i>Ropalidia marginata</i> species of insect

Ropalidia marginata is an Old World species of paper wasp. It is primitively eusocial, not showing the same bias in brood care seen in other social insects with greater asymmetry in relatedness. The species employees a variety of colony founding strategies, sometimes with single founders and sometimes in groups of variable number. The queen does not use physical dominance to control workers; there is evidence of pheromones being used to suppress other female workers from overtaking queenship.

External morphology of Lepidoptera The external features of butterflies and moths are described and explained.

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.

Crustacean larva crustacean larval and immature stages between hatching and adult form

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Ichthyoplankton The eggs and larvae of fish that drift in the water column

Ichthyoplankton are the eggs and larvae of fish. They are mostly found in the sunlit zone of the water column, less than 200 metres deep, which is sometimes called the epipelagic or photic zone. Ichthyoplankton are planktonic, meaning they cannot swim effectively under their own power, but must drift with the ocean currents. Fish eggs cannot swim at all, and are unambiguously planktonic. Early stage larvae swim poorly, but later stage larvae swim better and cease to be planktonic as they grow into juveniles. Fish larvae are part of the zooplankton that eat smaller plankton, while fish eggs carry their own food supply. Both eggs and larvae are themselves eaten by larger animals.

The Diptera is a very large and diverse order of mostly small to medium-sized insects. They have prominent compound eyes on a mobile head, and one pair of functional, membraneous wings, which are attached to a complex mesothorax. The second pair of wings, on the metathorax, are reduced to halteres. The order's fundamental peculiarity is its remarkable specialization in terms of wing shape and the morpho-anatomical adaptation of the thorax – features which lend particular agility to its flying forms. The filiform, stylate or aristate antennae correlate with the Nematocera, Brachycera and Cyclorrhapha taxa respectively. It displays substantial morphological uniformity in lower taxa, especially at the level of genus or species. The configuration of integumental bristles is of fundamental importance in their taxonomy, as is wing venation. It displays a complete metamorphosis, or holometabolous development. The larvae are legless, and have head capsules with mandibulate mouthparts in the Nematocera. The larvae of "higher flies" (Brachycera) are however headless and wormlike, and display only three instars. Pupae are obtect in the Nematocera, or coarcate in Brachycera.

References

  1. 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.
  2. 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.
  3. "Recognizing Insect Larval Types". University of Kentucky. Retrieved 28 April 2016.
  4. "Insect Larval Forms". About.com. Retrieved 28 April 2016.
  5. "Types of Insect Larva". Agri info. Archived from the original on 14 May 2016. Retrieved 28 April 2016.

Bibliography