A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians have a larval phase of their life cycle; the larva's appearance is very different from the adult form including different unique structures and organs that do not occur in the adult form. Their diet may be different. Larvae are adapted to environments separate from adults. For example, some larvae such as tadpoles live 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, 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 the males are capable of feeding larvae but they are much less efficient, spending more time and getting less food to the larvae. The larvae of some species do not develop further into the adult form; this is a type of neoteny. It is a misunderstanding; this could be the case, but the larval stage has evolved secondarily, as in insects. In these cases the larval form may differ more than the adult form from the group's common origin. Within Insects, only Endopterygotes show different types of larvae. Several classifications have been suggested by many entomologists, following classification is based on Antonio Berlese classification in 1913. There are four main types of endopterygote larvae types: Apodous larvae – no legs at all and are poorly sclerotized. Based on sclerotization, three apodous forms are recognized. Eucephalous – with well sclerotized head capsule. Found in Nematocera and Cerambycidae families. Hemicephalus – with a reduced head capsule, retractable in to the thorax.
Found in Tipulidae and Brachycera families. Acephalus – without head capsule. Found in Cyclorrhapha Protopod larvae – larva have many different forms and unlike a normal insect form, they hatch from eggs which contains little yolk. Ex. first instar larvae of parasitic hymenoptera. Polypod larvae – known as eruciform larvae, these larva have abdominal prolegs, in addition to usual thoracic legs, they poorly sclerotized and inactive. They live in close contact with the 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. Long legged predators with prognathous mouthparts.. Scarabeiform – poorly sclerotized, flat thorax and abdomen. Short legged and inactive burrowing forms.. Crustacean larvae Ichthyoplankton Spawn Non-larval animal juvenile stages and other life cycle stages: In Porifera: olynthus, gemmule In Cnidaria: ephyra, strobila, hydranth, medusa In Mollusca: paralarva, young cephalopods In Platyhelminthes: hydatid cyst In Bryozoa: avicularium In Acanthocephala: cystacanth In Insecta: Nymphs and naiads, immature forms in hemimetabolous insects Subimago, a juvenile that resembles the adult in Ephemeroptera Instar, intermediate between each ecdysis Pupa and chrysalis, intermediate stages between larva and imago Protozoan life cycle stages Apicomplexan life cycle Algal life cycle stages: Codiolum-phase Conchocelis-phase Marine larval ecology Media related to Larvae at Wikimedia Commons The dictionary definition of larva at Wiktionary Arenas-Mena, C.
Indirect development, transdifferentiation and the macroregulatory evolution of metazoans. Philosophical Transactions of the Royal Society B: Biological Sciences. Feb 27, 2010 Vol.365 no.1540 653-669 Brusca, R. C. & Brusca, G. J.. Invertebrates. Sunderland, Mass.: Sinauer Associates. Hall, B. K. & Wake, M. H. eds.. The Origin and Evolution of Larval Forms. San Diego: Academic Press. Leis, J. M. & Carson-Ewart, B. M. eds.. The Larvae of Indo-Pacific Coastal Fishes. An Identification Guide to Marine Fish Larvae. Fauna Malesiana handbooks, vol. 2. Brill, Leiden. Minelli, A.. The larva. In: Perspectives in Animal Phylogeny and Evolution. Oxford University Press. P. 160-170. Link. Shanks, A. L.. An Identification Guide to the Larval Marine Invertebrates of the Pacific Northwest. Oregon State University Press, Corvallis. 256 pp. Smith, D. & Johnson, K. B.. A Guide to Marine Coastal Plankton and Marine Invertebrate Larvae. Kendall/Hunt Plublishing Company. Stanwell-Smith, D. Hood, A. & Peck, L. S.. A field guide to the pelagic invertebrates larvae of the maritime Antarctic.
British Antarctic Survey, Cambridge. Thyssen, P. J.. Keys for Identification of Immature Insects. In: Amendt, J. et al.. Current Concepts in Forensic Entomology, chapter 2, pp. 25–42. Springer: Dordrecht
Flies are insects with a pair of functional wings for flight and a pair of vestigial hindwings called halteres for balance. They are classified as an order called Diptera, that name being derived from the Greek δι- di- "two", πτερόν pteron "wings"; the order Diptera is divided with about 110 families divided between them. The earliest fly fossils found so far are from the Triassic, about 240 million years ago. Many insects, such as the butterfly, contain the word are not Dipterans; the word "fly" is sometimes used colloquially and non-scientifically as a name for any small flying insect: the term "true fly" is sometimes invoked to make clear the insect being referenced is a Dipteran. Flies have a mobile head, with a pair of large compound eyes, mouthparts designed for piercing and sucking, or for lapping and sucking in the other groups; the suborder Nematocera have long antennae. Flies have only a single pair of wings to fly; the hindwings evolved into advanced mechanosensory organs, which act as high-speed sensors of rotational movement and allow them to perform advanced aerobatics.
Claws and pads on their feet enable them to cling to smooth surfaces. The life cycle of flies consists of the eggs, larva and the adult. Flies undergo complete metamorphosis; the pupa in higher dipterans is a tough capsule. Flies have short lives: for example, the adult housefly lives about a month; the source of nutrition for adult flies is liquified food, including nectar. Flies are of human importance, they are important pollinators, second only to their Hymenopteran relatives. They may have been responsible for the first plant pollination in the Triassic. Mosquitoes are vectors for malaria, West Nile fever, yellow fever and other infectious diseases. Flies can be annoyances in some parts of the world where they can occur in large numbers and settling on the skin or eyes to bite or seek fluids. Larger flies such as tsetse flies and screwworms cause significant economic harm to cattle. Blowfly larvae, known as gentles, other dipteran larvae, known more as maggots, are used as fishing bait, as food for carnivorous animals, in medicine for debridement to clean wounds.
Fruit flies are used as model organisms in research. In culture, the subject of flies appears in religion, literature and music. Dipterans are insects that undergo radical metamorphosis, they belong to the Mecopterida, alongside the Mecoptera, Siphonaptera and Trichoptera. The possession of a single pair of wings distinguishes most true flies from other insects with "fly" in their names. However, some true flies such as Hippoboscidae have become secondarily wingless; the cladogram represents the current consensus view. The first true dipterans known are from the Middle Triassic around 240 million years ago, they became widespread during the Middle and Late Triassic. Phylogenetic analysis of times of divergence suggests that dipterans originated in the Permian, some 260 million years ago. Modern flowering plants did not appear until the Cretaceous, so the original dipterans must have had a different source of nutrition other than nectar. Based on the attraction of many modern fly groups to shiny droplets, it has been suggested that they may have fed on honeydew produced by sap-sucking bugs which were abundant at the time, dipteran mouthparts are well-adapted to softening and lapping up the crusted residues.
The basal clades in the Diptera include the enigmatic Nymphomyiidae. Three episodes of evolutionary radiation are thought to have occurred based on the fossil record. Many new species of lower Diptera developed in the Triassic, about 220 million years ago. Many lower Brachycera appeared in the Jurassic, some 180 million years ago. A third radiation took place among the Schizophora at the start of the Paleogene, 66 million years ago; the phylogenetic position of Diptera has been controversial. The monophyly of holometabolous insects has long been accepted, with the main orders being established as Lepidoptera, Coleoptera and Diptera, it is the relationships between these groups which has caused difficulties. Diptera is thought to be a member of Mecopterida, along with Lepidoptera, Siphonaptera and Strepsiptera. Diptera has been grouped with Siphonaptera and Mecoptera in the Antliophora, but this has not been confirmed by molecular studies. Diptera were traditionally broken down into two suborders and Brachycera, distinguished by the differences in antennae.
The Nematocera are recognized by their elongated bodies and many-segmented feathery antennae as represented by mosquitoes and crane flies. The Brachycera have rounder bodies and much sh
A silverfish is a small, wingless insect in the order Zygentoma. Its common name derives from the animal's silvery light grey colour, combined with the fish-like appearance of its movements. However, the scientific name, indicates the silverfish's diet consists of carbohydrates such as sugar or starches. Silverfish are nocturnal insects 13–25 mm long, their abdomens taper at the end. The newly hatched develop a greyish hue and metallic shine as they get older, they have one terminal filament at the tips of their abdomens. They have two small compound eyes, despite other members of Zygentoma being eyeless, such as the family Nicoletiidae. Like other species in Apterygota, silverfish are wingless, they have long antennae, move in a wiggling motion that resembles the movement of a fish. This, coupled with their appearance and silvery scales, inspires their common name. Silverfish live for two to eight years. Silverfish can outrun most of their predators. However, such running is possible only on horizontal surfaces, as they lack any additional appendages, therefore are not fast enough to climb walls at the same speed.
They avoid light. Silverfish are a cosmopolitan species, found in Africa, the Americas, Australia and other parts of the Pacific, they inhabit moist areas, requiring a relative humidity between 75% and 95%. In urban areas, they can be found in attics, bathtubs, kitchens, old books, showers. Before silverfish reproduce, they carry out a ritual involving three phases, which may last over half an hour. In the first phase, the male and female stand face to face, their quivering antennae touching repeatedly back off and return to this position. In the second phase, the male runs away and the female chases him. In the third phase, the male and female stand side by side and head to tail, with the male vibrating his tail against the female; the male lays a spermatophore, a sperm capsule covered in gossamer, which the female takes into her body via her ovipositor to fertilize her eggs. The female deposited in small crevices; the eggs are oval-shaped, about 0.8 mm long, take between two weeks and two months to hatch.
A silverfish lays fewer than 100 eggs in her lifetime. When the nymphs hatch, they are whitish in colour, look like smaller adults; as they moult, young silverfish develop a greyish appearance and a metallic shine becoming adults after three months to three years. They may go through 17 to 66 moults in their lifetimes, sometimes 30 in a single year—many more than most insects. Silverfish are among the few types of insect. Silverfish consume matter that contains polysaccharides, such as dextrin in adhesives; these include book bindings, clothing, dandruff, hair, some paints, photos and sugar. They will damage wallpaper. Silverfish can cause damage to tapestries. Other substances they may eat include cotton, dead insects, silk, or their own exuvia. During famine, a silverfish may attack leatherware and synthetic fabrics. Silverfish can live for a year or more without eating. Silverfish are considered household pests, due to their destruction of property. However, although they are responsible for the contamination of food and other types of damage, they do not transmit disease.
Earwigs, house centipedes, spiders are known to be predators of silverfish. The scientific name for the species is Lepisma saccharina, due to its tendency to eat starchy foods high in carbohydrates and protein, such as dextrin. However, the insect's more common name comes from its distinctive metallic appearance and fish-like shape. While the scientific name can be traced back to 1758, the common name has been in use since at least 1855. Together with jumping bristletails, the predecessors of silverfish are considered the earliest, most primitive insects, they evolved at the latest in mid-Devonian and as early as late Silurian more than 400 million years ago. Some fossilized arthropod trackways from the Paleozoic Era, known as Stiaria intermedia and attributed to jumping bristletails, may have been produced by silverfish. Other similar insect species are known as silverfish. Two other silverfish are common in North America, Ctenolepisma longicaudata and Ctenolepisma quadriseriata. Ctenolepisma urbana is known as the urban silverfish.
The Australian species most referred to as silverfish is a different lepismatid, Acrotelsella devriesiana. The firebrat is with mottled gray and brown bodies. Fact sheet on silverfish highlighting habits and threats Klass, Carolyn. "Silverfish and Firebrats". Insect Diagnostic Laboratory. Cornell University. Retrieved 2015-11-16. Museumpests.net Silverfish factsheet
The mouthparts of arthropods have evolved into a number of forms, each adapted to a different style or mode of feeding. Most mouthparts represent modified, paired appendages, which in ancestral forms would have appeared more like legs than mouthparts. In general, arthropods have mouthparts for cutting, piercing, shredding and filtering; this article outlines the basic elements of four arthropod groups: insects, myriapods and chelicerates. Insects are used with the novel mouthparts of the other groups introduced in turn. Insects are not, the ancestral form of the other arthropods discussed here. Insect mouthparts exhibit a range of forms; the earliest insects had chewing mouthparts. Specialisation includes mouthparts modified for siphoning, piercing and sponging; these modifications have evolved a number of times. For example and aphids both pierce and suck; this section provides an overview of the individual mouthparts of chewing insects. The labrum is a flat extension of the head. Unlike other mouthparts, the labrum is a fused plate.
It located on the midline. It serves to hold food in place during chewing by the mandibles and thus can be described as an upper lip. Chewing insects have one on each side of the head, they are the largest mouthpart of chewing insects, being used to masticate food items. They come together medially. Paired maxillae cut food and manipulate it during mastication. Maxillae can have "teeth" along their inner margins. At the outer margin, the galea is a cupped or scoop-like structure, which sits over the outer edge of the labium, they have palps, which are used to sense the characteristics of potential foods. The labium is a single structure, it can be described as the floor of the functioning in close the mouth of the insect. With the maxillae, it assists manipulation of food during mastication; the hypopharynx is a somewhat globular structure, arising from the base of the labium. It assists swallowing, it performs the role of the tongue found in large vertebrates. Myriapods comprise four classes of each with a similar morphology: Class Chilopoda.
Myriapod mouthparts are similar to those of chewing insects, although there is some variation between the myriapod classes. A labrum is present but sometimes is not obvious and forms an upper lip in association with an epistome; the labium is formed by first maxillae in diplopoda forming the gnathochilarium. The preoral cavity so-formed contains any maxillae which are present. Centipedes, in addition to their mouthparts, forcipules. These, like the maxillipeds of crustaceans, are not true mouthparts; the forcipules arise to the midline. The tip is a pointed fang; the forcipules are used to envenomate prey. Crustaceans comprise a number of classes, with various feeding modes supported by a range of adaptions to the mouthparts. In general, crustaceans possess paired mandibles with opposing biting and grinding surfaces; the mandibles are followed by paired second maxillae. Both the mandibles and the maxillae have been variously modified in different crustacean groups for filter feeding with the use of setae.
Up to the first three pairs of legs are modified to maxillipeds, which assist manipulation of food items by passing food forward to the mandibles for chewing or to the maxillae for cutting into smaller pieces. Filter feeding crustaceans have setae on modified appendages. Filter feeding may have developed in association with swimming, with early morphological adaptions occurring on the appendages of the body trunk. Subsequent adaptions appear to have favoured forward filtering appendages. Filtering appendages generate water currents that bring food items into reach for collection by setae. Other setae may be used to brush the filtering setae clean, yet other setae may transport food items to the mouth. Barnacles have thoracic appendages modified for feeding, the cirri, which filter suspended food particles from water currents and pass the food to the mouth. Chelicerates comprise four classes of arthropod, with similar gross morphology but defining differences: Class Xiphosura. Chelicerates are in part defined by possessing chelicerate appendages, although crustaceans possess chelate appendages.
Chelicerates are more distinguished from other arthropods in lacking antennae and mandibles. Chelicerae are chelate appendages. For example, in horseshoe crabs, they are like pincers, whereas in spiders, they are hollow and contain venom glands and are used to inject venom to disable prey prior to feeding. In some spiders, the chelicerae have teeth, which are used to macerate prey items to assist digestion by secreted enzymes; those spiders without toothed chelicerae inject digestive enzymes directly into their prey. Mites and ticks have a range of chelicerae. Carnivores have chelicerae that tear and cru
Simple eye in invertebrates
A simple eye refers to a type of eye form or optical arrangement that contains a single lens. A "simple eye" is so called in distinction from a multi-lensed "compound eye", is not at all simple in the usual sense of the word; the eyes of humans and large animals, camera lenses are classed as "simple" because in both cases a single lens collects and focuses light onto the retina or film. Many insects have compound eyes consisting of multiple lenses, each focusing light onto a small number of retinula cells; the structure of an animal's eye is determined by the environment in which it lives, the behavioural tasks it must fulfill to survive. Arthropods differ in the habitats in which they live, as well as their visual requirements for finding food or conspecifics, avoiding predators. An enormous variety of eye designs are found in arthropods: they possess a wide variety of novel solutions to overcome visual problems or limitations; some jellyfish, sea stars and ribbonworms bear the simplest eyes, pigment spot ocelli, which have pigment distributed randomly and which have no additional structures such as a cornea and lens.
The apparent eye color in these animals is therefore black. However, other cnidaria have more complex eyes, including those of Cubomedusae which have distinct retina and cornea. Many snails and slugs have ocelli, either at the tips or at the bases of the tentacles. However, some other gastropods, such as the Strombidae, have much more sophisticated eyes. Giant clams have ocelli. Spiders do not have compound eyes, but instead have several pairs of simple eyes with each pair adapted for a specific task or tasks; the principal and secondary eyes in spiders are arranged in four or more pairs. Only the principal eyes have moveable retinas; the secondary eyes have a reflector at the back of the eyes. The light-sensitive part of the receptor cells is next to this, so they get direct and reflected light. In hunting or jumping spiders, for example, a forward-facing pair possesses the best resolution to see the prey at a large distance. Night-hunting spiders' eyes are sensitive in low light levels with a large aperture, f/0.58.
The term "ocellus" is derived from the Latin oculus, means "little eye". Two distinct ocellus types exist: dorsal ocelli, found in most insects, lateral ocelli, which are found in the larvae of some insect orders, they are structurally and functionally different. Simple eyes of other animals, e.g. cnidarians, may be referred to as ocelli, but again the structure and anatomy of these eyes is quite distinct from those of the dorsal ocelli of insects. Dorsal ocelli are light-sensitive organs found on the dorsal surface or frontal surface of the head of many insects, e.g. Hymenoptera, Diptera and Orthoptera; the ocelli coexist with the compound eyes. The number and functions of the dorsal ocelli vary markedly throughout insect orders, they tend to be larger and more expressed in flying insects, where they are found as a triplet. Two lateral ocelli are directed to the left and right of the head while a central ocellus is directed frontally. In some terrestrial insects, only two lateral ocelli are present: the median ocellus is absent.
The labelled "lateral ocelli" here refers to the sideways-facing position of the ocelli, which are of the dorsal type. They should not be confused with the lateral ocelli of some insect larvae. A dorsal ocellus consists of a layer of photoreceptors; the ocellar lens may be curved or flat. The photoreceptor layer may not be separated from the lens by a clear zone; the number of photoreceptors varies but may number in the hundreds or thousands for well-developed ocelli. Two somewhat unusual features of the ocelli are notable and well conserved between insect orders; the refractive power of the lens is not sufficient to form an image on the photoreceptor layer. Dorsal ocelli ubiquitously have massive convergence ratios from first-order to second-order neurons; these two factors have led to the conclusion that the dorsal ocelli are incapable of perceiving form, are thus suitable for light-metering functions. Given the large aperture and low f-number of the lens, as well as high convergence ratios and synaptic gains, the ocelli are considered to be far more sensitive to light than the compound eyes.
Additionally, given the simple neural arrangement of the eye, as well as the large diameter of some ocellar interneurons, the ocelli are considered to be "faster" than the compound eyes. One common theory of ocellar function in flying insects holds that they are used to assist in maintaining flight stability. Given their underfocused nature, wide fields of view, high light-collecting ability, the ocelli are superbly adapted for measuring changes in the perceived brightness of the external world as an insect rolls or pitches arou
A wasp is any insect of the order Hymenoptera and suborder Apocrita, neither a bee nor an ant. The Apocrita form a clade; the most known wasps, such as yellowjackets and hornets, are in the family Vespidae and are eusocial, living together in a nest with an egg-laying queen and non-reproducing workers. Eusociality is favoured by the unusual haplodiploid system of sex determination in Hymenoptera, as it makes sisters exceptionally related to each other. However, the majority of wasp species are solitary, with each adult female living and breeding independently. Females have an ovipositor for laying eggs in or near a food source for the larvae, though in the Aculeata the ovipositor is modified instead into a sting used for defense or prey capture. Wasps play many ecological roles; some are pollinators, whether to feed themselves or to provision their nests. Many, notably the cuckoo wasps, are kleptoparasites. Many of the solitary wasps are parasitoidal, meaning they lay eggs on or in other insects and provision their own nests with such hosts.
Unlike true parasites, the wasp larvae kill their hosts. Solitary wasps parasitize every pest insect, making wasps valuable in horticulture for biological pest control of species such as whitefly in tomatoes and other crops. Wasps first appeared in the fossil record in the Jurassic, diversified into many surviving superfamilies by the Cretaceous, they are a diverse group of insects with tens of thousands of described species. The largest social wasp is the Asian giant hornet, at up to 5 centimetres in length; the smallest wasps are solitary chalcid wasps in the family Mymaridae, including the world's smallest known insect, with a body length of only 0.139 mm, the smallest known flying insect, only 0.15 mm long. Wasps have appeared in literature from Classical times, as the eponymous chorus of old men in Aristophanes' 422 BC comedy Σφῆκες, The Wasps, in science fiction from H. G. Wells's 1904 novel The Food of the Gods and How It Came to Earth, featuring giant wasps with three-inch-long stings.
The name "Wasp" has been used for other military equipment. The wasps are a cosmopolitan paraphyletic grouping of hundreds of thousands of species, consisting of the narrow-waisted Apocrita without the ants and bees; the Hymenoptera contain the somewhat wasplike but unwaisted Symphyta, the sawflies. The term wasp is sometimes used more narrowly for the Vespidae, which includes the common wasp or yellow jacket genera Vespula and Dolichovespula and the hornets, Vespa. Hymenoptera in the form of Symphyta first appeared in the fossil record in the Lower Triassic. Apocrita, wasps in the broad sense, appeared in the Jurassic, had diversified into many of the extant superfamilies by the Cretaceous. Fig wasps with modern anatomical features first appeared in the Lower Cretaceous of the Crato Formation in Brazil, some 65 million years before the first fig trees; the Vespidae include the extinct genus Palaeovespa, seven species of which are known from the Eocene rocks of the Florissant fossil beds of Colorado and from fossilised Baltic amber in Europe.
Found in Baltic amber are crown wasps of the genus Electrostephanus. Wasps are a diverse group, estimated at over a hundred thousand described species around the world, a great many more as yet undescribed. For example, there are over 800 species of fig trees in the tropics, all of these has its own specific fig wasp to effect pollination. Many wasp species are parasitoids; some larvae start off as parasitoids, but convert at a stage to consuming the plant tissues that their host is feeding on. In other species, the eggs are laid directly into plant tissues and form galls, which protect the developing larvae from predators but not from other parasitic wasps. In some species, the larvae are predatory themselves; the largest social wasp is the Asian giant hornet, at up to 5 centimetres in length. The various tarantula hawk wasps are of a similar size and can overpower a spider many times its own weight, move it to its burrow, with a sting, excruciatingly painful to humans; the solitary giant scoliid, Megascolia procer, with a wingspan of 11.5 cm, has subspecies in Sumatra and Java.
The female giant ichneumon wasp Megarhyssa macrurus is 12.5 centimetres long including its long but slender ovipositor, used for boring into wood and inserting eggs. The smallest wasps are solitary chalcid wasps in the family Mymaridae, including the world's smallest known insect, Dicopomorpha echmepterygis and Kikiki huna with a body length of only 158 micrometres, the smallest known flying insect. There are estimated to be 100,000 species of ichneumonoid wasps in the families Braconidae and Ichneumonidae; these are exclusively parasitoids utilising other insects as hosts. Another family, the Pompilidae, is a specialist parasitoid of spiders; some wasps
A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea and photoreceptor cells which distinguish brightness and color; the image perceived by the arthropod is a combination of inputs from the numerous ommatidia, which are oriented to point in different directions. Compared with single-aperture eyes, compound eyes have poor image resolution. Compound eyes are classified as either apposition eyes, which form multiple inverted images, or superposition eyes, which form a single erect image. Apposition eyes can be divided into two groups; the typical apposition eye has a lens focusing light from one direction on the rhabdom, while light from other directions is absorbed by the dark wall of the ommatidium. The mantis shrimp is the most advanced example of an animal with this type of eye. In the other kind of apposition eye, found in the Strepsiptera, each lens forms an image, the images are combined in the brain.
This is called the neural superposition eye. The second type is named the superposition eye; the superposition eye is divided into three types. The refracting superposition eye has a gap between the lens and the rhabdom, no side wall; each lens reflects it to the same angle on the other side. The result is an image at half the radius of the eye, where the tips of the rhabdoms are; this kind is used by nocturnal insects. In the parabolic superposition compound eye type, seen in arthropods such as mayflies, the parabolic surfaces of the inside of each facet focus light from a reflector to a sensor array. Long-bodied decapod crustaceans such as shrimp, prawns and lobsters are alone in having reflecting superposition eyes, which have a transparent gap but use corner mirrors instead of lenses. Good fliers like flies or honey bees, or prey-catching insects like praying mantis or dragonflies, have specialized zones of ommatidia organized into a fovea area which gives acute vision. In the acute zone the eye is flattened and the facets larger.
The flattening allows more ommatidia to receive light from a spot and therefore higher resolution. There are some exceptions from the types mentioned above; some insects have a so-called single lens compound eye, a transitional type, something between a superposition type of the multi-lens compound eye and the single lens eye found in animals with simple eyes. There is the mysid shrimp, Dioptromysis paucispinosa; the shrimp has an eye of the refracting superposition type, in the rear behind this in each eye there is a single large facet, three times in diameter the others in the eye and behind this is an enlarged crystalline cone. This projects an upright image on a specialized retina; the resulting eye is a mixture of a simple eye within a compound eye. Another version is the pseudofaceted eye; this type of eye consists of a cluster of numerous ocelli on each side of the head, organized in a way that resembles a true compound eye. The body of Ophiocoma wendtii, a type of brittle star, was thought to be covered with ommatidia, turning its whole skin into a compound eye.
Asymmetries in compound eyes may be associated with asymmetries in behaviour. For example, Temnothorax albipennis ant scouts show behavioural lateralization when exploring unknown nest sites, showing a population-level bias to prefer left turns. One possible reason for this is that its environment is maze-like and turning in one direction is a good way to search and exit mazes without getting lost; this turning bias is correlated with slight asymmetries in the ants' compound eyes. Pseudopupil Arthropod eye Ommatidium Eye Media related to Compound eye at Wikimedia Commons The Compound Eye Make Your Own Compound Eye by Stephanie Bailey Did you know that shrimps blink