An ocellus (plural: ocelli) is a type of photoreceptor organ in animals. Also called "simple eyes", ocelli are miniature eyes capable just of sensing light but not of distinguishing its direction. Photoreceptors are light-sensitive proteins involved in the function of photoreceptor cells. ... This article refers to the sight organ. ...
Ocelli are found in many invertebrates. Insects in particular have two types of ocelli: dorsal ocelli are light-sensitive organs on the dorsal surface or on the top of the head. They consist of a few tens of rod cells covered with a corneal lens. Insects with dorsal ocelli also have compound eyes, but lateral ocelli are the only eyes of the larvae of several orders of insects (fleas, springtails, silverfish, and Strepsiptera). Lateral occlli have a mixture of rod cells and cone cells and are found on the sides of the head, one to six on each side. Invertebrate is a term coined by Chevalier de Lamarck to describe any animal without a backbone or vertebra, like insects, squids and worms. ... A database query syntax error has occurred. ... Normalised absoption spectra of human rod (R) and cone (S,M,L) cells. ... The cornea is the curved, transparent layer that covers the front part of the eye and protects its inner structures. ... Compound eye of a dragonfly Compound eye of Antarctic krill as imaged by an electron microscope A compound eye is a visual organ found in certain arthropods such as some insects and crustaceans. ... Families Tungidae - Sticktight and Chigoe fleas Pulicidae - Common fleas Coptopsyllidae Vermipsyllidae - Carnivore fleas Rhopalopsyllidae - Marsupial fleas Hypsophthalmidae Stephanocircidae Pygiopsyllidae Hystrichopsyllidae - Rat and mouse fleas Leptopsyllidae - Bird and rabbit fleas Ischnopsyllidae - Bat fleas Ceratophyllidae Amphipsyllidae Malacopsyllidae Dolichopsyllidae - Rodent fleas Ctenopsyllidae Flea is the common name for any of the small wingless... Families Suborder Arthropleona Superfamily Entomobryoidea Entomobryidae - slender springtails Isotomidae - smooth springtails Oncopoduridae Paronellidae Tomoceridae Superfamily Poduroidea Brachystomellidae Hypogastruridae - elongate-bodied springtails Neanuridae Odontellidae Onychiuridae - blind springtails Poduridae - water springtails Suborder Symphypleona Dicyrtomidae Katiannidae Sminthuridae - globular springtails Sminthurididae Bourletiellidae Arrhopalitidae Springtails (Order Collembola) form the largest of the three orders of... Families Lepidotrichidae Nicoletiidae Lepismatidae This page is about the Silverfish insect. ... Families Mengenillidae Mengeidae Stylopidae Bohartillidae Corioxenidae Halictophagidae Callipharixenidae Elenchidae Myrmecolacidae The Strepsiptera are a small (~300 species) order of insects. ... Normalised absoption spectra of human rod (R) and cone (S,M,L) cells. ... Normalised absorption spectra of human cone (S,M,L) and rod (R) cells Cone cells, or cones, are cells in the retina which only function in relatively bright light. ...
In the ocellus there were two peaks: one of UV light at a wavelength of 335-340 nm and one of green light at 490 nm whereas in compound eyes the peaks were at 350 nm and 540 nm (Goldsmith and Ruck, 1958).
Generally speaking the distribution of melanin in the ocellus is primarily in the outer envelope and in the retimalar cellsaround the distal part of the rhabdom.
The ocellus tends to accumulate heat owing to the rapid metabolic process as well as to solar irradiation which is concentrated in the ocellus by the transparent cornea (which acts as a concentrating lens) and therefore flow of hemolymph is important for cooling of the ocellus.
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