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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, [3] or a handful in the primitive Zygentoma, to around 30,000 in larger Anisoptera dragonflies and some Sphingidae moths.
Most arthropods have at least one of two types of eye: lateral compound eyes, and smaller median ocelli, which are simple eyes. [2] When both are present, the two eye types are used in concert because each has its own advantage. [3] Some insect larvae, e.g., caterpillars, have a different type of simple eye known as stemmata.
Arthropod eyes Head of a wasp with three ocelli (center), and compound eyes at the left and right. Most arthropods have sophisticated visual systems that include one or more usually both of compound eyes and pigment-cup ocelli ("little eyes"). In most cases, ocelli are only capable of detecting the direction from which light is coming, using ...
Compound eye of a house centipede Compound eye of a dragonfly. A compound eye is a visual organ found in arthropods such as insects and crustaceans.It may consist of thousands of ommatidia, [1] which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distinguish brightness and color.
Holoptic refers to one of the ways in which the arthropod eye develops, particularly the eyes of various species of insects. Unlike dichoptic and cycloptic eyes, holoptic eyes meet along the median dorsal line of the head, in many species nearly covering the exterior of the head.
Uniramia (uni – one, ramus – branch, i.e. single-branches) is a group within the arthropods. In the past this group included the Onychophora, which are now considered a separate category. The group is currently used in a narrower sense. [2] Onychophora like this Peripatoides sp. are no longer counted as unirames.
A simple eye or ocellus (sometimes called a pigment pit [1] [2]) is a form of eye or an optical arrangement which has a single lens without the sort of elaborate retina that occurs in most vertebrates. These eyes are called "simple" to distinguish them from "compound eyes", which have multiple lenses. They are not necessarily simple in the ...
In the "higher" Diptera the head has a subglobose shape and the fronto-clypeus is an area bounded superiorly by the eyes and the vertex. In Cyclorrhapha Schizophora , a morphological element of particular importance is the presence of the ptilinal suture formed by the resorption of the ptilinum after emergence from the pupa.