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A compound eye is a visual organ found in
arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...
s such as
insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...
s and
crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...
s. It may consist of thousands of
ommatidia The compound eyes of arthropods like insects, crustaceans and millipedes are composed of units called ommatidia (singular: ommatidium). An ommatidium contains a cluster of photoreceptor cells surrounded by support cells and pigment cells. The ou ...
, which are tiny independent photoreception units that consist of a
cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power ...
,
lens A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), ...
, and
photoreceptor cell A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction. The great biological importance of photoreceptors is that they convert light (visible electromagnetic radiatio ...
s which distinguish brightness and color. The image perceived by this
arthropod eye Apposition eyes are the most common form of eye, and are presumably the ancestral form of compound eye. They are found in all arthropod groups, although they may have evolved more than once within this phylum. Some annelids and bivalves also h ...
is a combination of inputs from the numerous ommatidia, which are oriented to point in slightly different directions. Compared with single-aperture
eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...
s, compound eyes have poor
image resolution Image resolution is the detail an image holds. The term applies to digital images, film images, and other types of images. "Higher resolution" means more image detail. Image resolution can be measured in various ways. Resolution quantifies how ...
; however, they possess a very large view angle and the ability to detect fast movement and, in some cases, the polarization of light. Because a compound eye is made up of a collection of ommatidia, each with its own lens, light will enter each ommatidium instead of using a single entrance point. The individual light receptors behind each lens are then turned on and off due to a series of changes in the light intensity during movement or when an object in moving, creating a flicker-effect known as the flicker frequency, which is the rate at which the ommotadia are turned on and off– this facilitates faster reaction to movement;
honey bee A honey bee (also spelled honeybee) is a eusocial flying insect within the genus ''Apis'' of the bee clade, all native to Afro-Eurasia. After bees spread naturally throughout Africa and Eurasia, humans became responsible for the current co ...
s respond in 0.01s compared with 0.05s for humans .


Types

Compound eyes are typically classified as either apposition eyes, which form multiple inverted images, or superposition eyes, which form a single erect image.


Apposition eyes

Apposition eyes can be divided into two groups. The typical apposition eye has a lens focusing light from one direction on the
rhabdom The compound eyes of arthropods like insects, crustaceans and millipedes are composed of units called ommatidia (singular: ommatidium). An ommatidium contains a cluster of photoreceptor cells surrounded by support cells and pigment cells. The ou ...
, while light from other directions is absorbed by the dark wall of the
ommatidium The compound eyes of arthropods like insects, crustaceans and millipedes are composed of units called ommatidia (singular: ommatidium). An ommatidium contains a cluster of photoreceptor cells surrounded by support cells and pigment cells. The ou ...
. The
mantis shrimp Mantis shrimp, or stomatopods, are carnivorous marine crustaceans of the order Stomatopoda (). Stomatopods branched off from other members of the class Malacostraca around 340 million years ago. Mantis shrimp typically grow to around in lengt ...
is the most advanced example of an animal with this type of eye. In the other kind of apposition eye, found in the
Strepsiptera The Strepsiptera are an order of insects with eleven extant families that include about 600 described species. They are endoparasites in other insects, such as bees, wasps, leafhoppers, silverfish, and cockroaches. Females of most species never ...
, each lens forms an image, and the images are combined in the brain. This is called the schizochroal compound eye or the neural superposition eye (which, despite its name, is a form of the apposition eye).


Superposition eyes

The superposition eye is divided into three subtypes; the ''refracting'', the ''reflecting'', and the ''parabolic'' superposition eye. The refracting superposition eye has a gap between the lens and the rhabdom, and no side wall. Each lens takes light at an angle to its axis and reflects it to the same angle on the other side. The result is an image at half the radius of the eye, which is where the tips of the rhabdoms are. This kind is used mostly by nocturnal insects. In the parabolic superposition eye, seen in arthropods such as
mayflies Mayflies (also known as shadflies or fishflies in Canada and the upper Midwestern United States, as Canadian soldiers in the American Great Lakes region, and as up-winged flies in the United Kingdom) are aquatic insects belonging to the orde ...
, 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 Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...
,
prawn Prawn is a common name for small aquatic crustaceans with an exoskeleton and ten legs (which is a member of the order decapoda), some of which can be eaten. The term "prawn"Mortenson, Philip B (2010''This is not a weasel: a close look at nature ...
s,
crayfish Crayfish are freshwater crustaceans belonging to the clade Astacidea, which also contains lobsters. In some locations, they are also known as crawfish, craydids, crawdaddies, crawdads, freshwater lobsters, mountain lobsters, rock lobsters, mu ...
and
lobster Lobsters are a family (biology), family (Nephropidae, Synonym (taxonomy), synonym Homaridae) of marine crustaceans. They have long bodies with muscular tails and live in crevices or burrows on the sea floor. Three of their five pairs of legs ...
s are alone in having reflecting superposition eyes, which also have a transparent gap but use
corner mirror A corner reflector is a retroreflector consisting of three mutually perpendicular, intersecting flat surfaces, which reflects waves directly towards the source, but translated. The three intersecting surfaces often have square shapes. Radar co ...
s instead of lenses.


Other

Good fliers like flies or honey bees, or prey-catching insects like
praying mantis Mantises are an order (Mantodea) of insects that contains over 2,400 species in about 460 genera in 33 families. The largest family is the Mantidae ("mantids"). Mantises are distributed worldwide in temperate and tropical habitats. They ha ...
es or
dragonflies A dragonfly is a flying insect belonging to the infraorder Anisoptera below the order Odonata. About 3,000 extant species of true dragonfly are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threa ...
, have specialized zones of
ommatidia The compound eyes of arthropods like insects, crustaceans and millipedes are composed of units called ommatidia (singular: ommatidium). An ommatidium contains a cluster of photoreceptor cells surrounded by support cells and pigment cells. The ou ...
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 which is something between a superposition type of the multi-lens compound eye and the single lens eye found in animals with simple eyes. Then there is the
mysid Mysida is an order of small, shrimp-like crustaceans in the malacostracan superorder Peracarida. Their common name opossum shrimps stems from the presence of a brood pouch or "marsupium" in females. The fact that the larvae are reared in thi ...
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 that is 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, as seen in
Scutigera ''Scutigera'' is a centipede genus in the scutigeromorph (house centipede) family Scutigeridae, a group of centipedes with long limbs and true compound eyes (which were once thought to be secondary, re-evolved "pseudofacetted eyes"). It compose ...
. This type of eye consists of a cluster of numerous
ocelli A simple eye (sometimes called a pigment pit) refers to a form of eye or an optical arrangement composed of a single lens and without an elaborate retina such as occurs in most vertebrates. In this sense "simple eye" is distinct from a multi-l ...
on each side of the head, organized in a way that resembles a true compound eye. Asymmetries in compound eyes may be associated with asymmetries in behaviour. For example, ''
Temnothorax albipennis ''Temnothorax albipennis'', the rock ant is a species of small ant in the subfamily Myrmicinae. It occurs in Europe and builds simple nests in rock crevices. Description This species has the typical ant body pattern of head, mesosoma and metasom ...
'' 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 partly maze-like and consistently 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 (differential ommatidia count). The body of '' Ophiomastix wendtii'', a type of
brittle star Brittle stars, serpent stars, or ophiuroids (; ; referring to the serpent-like arms of the brittle star) are echinoderms in the class Ophiuroidea, closely related to starfish. They crawl across the sea floor using their flexible arms for locomo ...
, was previously thought to be covered with ommatidia, turning its whole skin into a compound eye, but this has since been found to be erroneous; the system does not rely on lenses or image formation.


See also

*
Pseudopupil In the compound eye of invertebrates such as insects and crustaceans, the pseudopupil appears as a dark spot which moves across the eye as the animal is rotated. This occurs because the ommatidia that one observes "head-on" (along their optica ...
*
Arthropod eye Apposition eyes are the most common form of eye, and are presumably the ancestral form of compound eye. They are found in all arthropod groups, although they may have evolved more than once within this phylum. Some annelids and bivalves also h ...
*
Ommatidium The compound eyes of arthropods like insects, crustaceans and millipedes are composed of units called ommatidia (singular: ommatidium). An ommatidium contains a cluster of photoreceptor cells surrounded by support cells and pigment cells. The ou ...
*
Eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...


Cultural references

"Dragonfly eyes" (Chinese: 蜻蜓眼 ''qingting yan''] is a term for knobbly multi-coloured glass beads made in Western and Eastern Asia 2000–2500 years ago.https://www.cambridge.org/core/journals/microscopy-and-microanalysis/article/abs/nondestructive-analysis-of-dragonfly-eye-beads-from-the-warring-states-period-excavated-from-a-chu-tomb-at-the-shenmingpu-site-henan-province-china/E2FCF854D5324115F503E1643C33BDBD DOI: https://doi.org/10.1017/S1431927612014201 Owing to the multiple views and stimuli, compound eyes or dragonfly eyes have become a feature in art, film and literature, particularly in the 2010s. For example: * The Man with the Compound Eyes, novel (2011) by
Wu Ming-yi Wu Ming-yi (; born 20 June 1971) is a multidisciplinary Taiwanese artist, author, Professor of Sinophone literature at National Dong Hwa University and environmental activist. His ecological parable '' The Man with the Compound Eyes'' (2011) w ...
, English translation (2013) by Darryl Sterk
''Dragonfly Eyes''
movie (2017) by
Xu Bing Xu Bing (; born 1955) is a Chinese artist who served as vice-president of the Central Academy of Fine Arts. He is known for his printmaking skills and installation art, as well as his creative artistic use of language, words, and text and how t ...

''Dragonfly Eyes''
novel (2016) by
Cao Wenxuan Cao Wenxuan (; born January 1954) is a Chinese novelist, best known for his works of children's literature. Cao is the vice president of Beijing Writers Association. He is also a professor and doctoral tutor at Peking University. His novels have ...
, English translation (2021) by
Helen Wang Helen Kay Wang (; ; born 1965) is an English sinologist and translator. She works as curator of East Asian Money at the British Museum in London. She has also published a number of literary translations from Chinese, including an award-winning tr ...


References


External links

*
The Compound Eye
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