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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 optical axes) absorb the incident light, while those to one side reflect it. The pseudopupil therefore reveals which ommatidia are aligned with the axis along which the observer is viewing. Pseudopupil analysis technique The pseudopupil analysis technique is used to study neurodegeneration in insects like ''Drosophila ''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species ....'' An adult ''Drosophila'' eye consists of nearly 800 unit ommatidia which are repeated in a symmetrical pattern. Each ommatidium contains 8 photoreceptor cells each of which form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 outer part of the ommatidium is overlaid with a transparent cornea. Each ommatidium is innervated by one axon bundle (usually consisting of 6–9 axons, depending on the number of rhabdomeres) and provides the brain with one picture element. The brain forms an image from these independent picture elements. The number of ommatidia in the eye depends upon the type of arthropod and range from as low as 5 as in the Antarctic isopod ''Glyptonotus antarcticus'', or a handful in the primitive Zygentoma, to around 30,000 in larger Anisoptera dragonflies and some Sphingidae moths. Description Ommatidia are typically hexagonal in cross-section and approximately ten times longer than wide. The diameter is largest at the surface, tapering toward the in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compound Eye
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, lens, and photoreceptor cells which distinguish brightness and color. The image perceived by this arthropod eye is a combination of inputs from the numerous ommatidia, which are oriented to point in slightly different directions. Compared with single-aperture eyes, compound eyes have poor image resolution; 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 flic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudosquilla
''Pseudosquilla ciliata'', the common mantis shrimp, is a species of mantis shrimp, known by common names including rainbow mantis shrimp and false mantis shrimp. It is widespread in the tropical Indo-Pacific region and in both the western and eastern Atlantic Ocean. Description ''P. ciliata'' can be distinguished from other closely related mantis shrimps by several characteristics; the eye is cylindrical with a hemispherical cornea; the rostral plate lacks a small spine at the front; the carapace does not bear large black spots; the telson has three keel-like ridges on either side of a central ridge; and the base of each uropod terminates in two slender flattened spines, the innermost of which is the shorter. The colour of ''P. ciliata'' varies greatly depending on an individual's environment; for example, ''P. ciliata'' living in a sea grass flat will often turn green, while one living in coralline algae will often turn red. ''P. ciliata'' may reach a total length of . The colo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Invertebrate
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate subphylum Vertebrata. Familiar examples of invertebrates include arthropods, mollusks, annelids, echinoderms and cnidarians. The majority of animal species are invertebrates; one estimate puts the figure at 97%. Many invertebrate taxa have a greater number and variety of species than the entire subphylum of Vertebrata. Invertebrates vary widely in size, from 50 μm (0.002 in) rotifers to the 9–10 m (30–33 ft) colossal squid. Some so-called invertebrates, such as the Tunicata and Cephalochordata, are more closely related to vertebrates than to other invertebrates. This makes the invertebrates paraphyletic, so the term has little meaning in taxonomy. Etymology The word "invertebrate" comes from the Latin word ''vertebra'', whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 of jointed legs, compound eyes and one pair of antennae. Their blood is not totally contained in vessels; some circulates in an open cavity known as the haemocoel. Insects are the most diverse group of animals; they include more than a million described species and represent more than half of all known living organisms. The total number of extant species is estimated at between six and ten million; In: potentially over 90% of the animal life forms on Earth are insects. Insects may be found in nearly all environments, although only a small number of species reside in the oceans, which are dominated by another arthropod group, crustaceans, which recent research has indicated insects are nested within. Nearly all insects hatch from eggs. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 can be treated as a subphylum under the clade Mandibulata. It is now well accepted that the hexapods emerged deep in the Crustacean group, with the completed group referred to as Pancrustacea. Some crustaceans (Remipedia, Cephalocarida, Branchiopoda) are more closely related to insects and the other hexapods than they are to certain other crustaceans. The 67,000 described species range in size from '' Stygotantulus stocki'' at , to the Japanese spider crab with a leg span of up to and a mass of . Like other arthropods, crustaceans have an exoskeleton, which they moult to grow. They are distinguished from other groups of arthropods, such as insects, myriapods and chelicerates, by the possession of biramous (two-parted) limbs, and by th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Axis
An optical axis is a line along which there is some degree of rotational symmetry in an optical system such as a camera lens, microscope or telescopic sight. The optical axis is an imaginary line that defines the path along which light propagates through the system, up to first approximation. For a system composed of simple lenses and mirrors, the axis passes through the center of curvature of each surface, and coincides with the axis of rotational symmetry. The optical axis is often coincident with the system's mechanical axis, but not always, as in the case of off-axis optical systems. For an optical fiber, the optical axis is along the center of the fiber core, and is also known as the ''fiber axis''. See also * Ray (optics) * Cardinal point (optics) * Antenna boresight In telecommunications and radar engineering, antenna boresight is the axis of maximum gain (maximum radiated power) of a directional antenna. For most antennas the boresight is the axis of symmetry of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Incident Light
In optics a ray is an idealized geometrical model of light, obtained by choosing a curve that is perpendicular to the ''wavefronts'' of the actual light, and that points in the direction of energy flow. Rays are used to model the propagation of light through an optical system, by dividing the real light field up into discrete rays that can be computationally propagated through the system by the techniques of '' ray tracing''. This allows even very complex optical systems to be analyzed mathematically or simulated by computer. Ray tracing uses approximate solutions to Maxwell's equations that are valid as long as the light waves propagate through and around objects whose dimensions are much greater than the light's wavelength. ''Ray optics'' or ''geometrical optics'' does not describe phenomena such as diffraction, which require wave optics theory. Some wave phenomena such as interference can be modeled in limited circumstances by adding phase to the ray model. Definition A li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Journal Of Experimental Biology
''Journal of Experimental Biology'' (formerly ''The British Journal of Experimental Biology)'' is a peer-reviewed scientific journal in the field of comparative physiology and integrative biology. It is published by The Company of Biologists. The journal is partnered with Publons and has two-way integration with bioRxiv. ''Journal of Experimental Biology'' is now a hybrid journal and publishes 24 issues a year. Content over six months old is free to read. History ''The'' ''British Journal of Experimental Biology'' was established in Edinburgh in 1923 (''Br. J. Exp. Biol.'': ). It was published by Oliver and Boyd and edited by F. A. E. Crew with an Editorial Board of nine members, including Julian Huxley. When the journal ran into financial trouble, George Parker Bidder II, the founder of The Company of Biologists, rescued it in 1925. Sir James Gray was appointed as the journal's first Editor-in-Chief in 1925 and the journal was renamed ''The Journal of Experimental Biology'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila
''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit. They should not be confused with the Tephritidae, a related family, which are also called fruit flies (sometimes referred to as "true fruit flies"); tephritids feed primarily on unripe or ripe fruit, with many species being regarded as destructive agricultural pests, especially the Mediterranean fruit fly. One species of ''Drosophila'' in particular, ''D. melanogaster'', has been heavily used in research in genetics and is a common model organism in developmental biology. The terms "fruit fly" and "''Drosophila''" are often used synonymously with ''D. melanogaster'' in modern biological literature. The entire genus, however, contains more than 1,500 species and is very diverse in appearance, be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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