| Ocelli |
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with three ocelli (centre), and the Dorsal part of Compound Eyes (left)]] An ocellus (plural: '''ocelli''') is a type of Photoreceptor organ in animals. Also called "simple eyes", ocelli are miniature Eyes capable of sensing light but not distinguishing its direction. See also Stemmata , which are structurally similar. Ocelli are found in many Invertebrate s. Insect s in particular have two types of ocelli, '''dorsal ocelli''' and '''lateral ocelli'''. PHOTORECEPTORS In Insect s, ocelli are involved (along with Compound Eye s) in the horizon-detecting response, decreasing the latency between horizon changes and the Insect 's response. Dorsal Ocelli Dorsal ocelli are light-sensitive organs on the Dorsal surface or on the top of the head. There are generally three, forming a triangle. They consist of a few dozen Rod Cell s covered with a Cornea l lens. In some species, such as Locust s, dorsal ocelli may contain several hundreds of retinula cells. Insects with dorsal ocelli also have Compound Eye s. Lateral Ocelli Lateral ocelli have a mixture of Rod Cell s and Cone Cell s and are found on the sides of the head, one to six on each side. Lateral ocelli are the only eyes of the larvae of several orders of insects ( Flea s, Springtail s, Silverfish , and Strepsiptera ). EXTERNAL LINKS
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