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Compound eye of Antarctic krill as imaged by an electron microscope. 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.
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 ...
While most crustacean and some insect larvae possess only simple median eyes, such as the Bolwig organs of Drosophila and the naupliar eye of most crustaceans, several groups have larvae with simple or compound lateral eyes. The compound eyes of adults develop in a region of the head separate from the region in which the larval median eye ...
Although composed of over 16,000 cells, [6] the Drosophila compound eye is a simple repetitive pattern of 700 to 750 ommatidia, [7] initiated in the larval eye imaginal disc. Each ommatidium consists of 14 neighboring cells: 8 photoreceptor neurons in the core, 4 non-neuronal cone cells and 2 primary pigment cells. [ 6 ]
Adult Lepidoptera have two immobile, multi-faceted compound eyes, and only two simple eyes or ocelli, which may be reduced. [5] The three segments of the thorax are fused together. Antennae are prominent and besides the faculty of smell, also aid navigation, orientation, and balance during flight. [6]
There are two large compound eyes, three ocelli (simple eyes) and a pair of antennae of variable lengths, set between or in front of the eyes. The mouthparts are designed for chewing and consist of a flap-like labrum , a pair of strong mandibles , a pair of maxillae , a membranous hypopharynx and a labium .
Compared with simple eyes, compound eyes possess very large view angles and better acuity than the insect's dorsal ocelli, but some stemmatal (= larval eyes), for example, those of sawfly larvae (Tenthredinidae) with an acuity of 4 degrees and very high polarization sensitivity, match the performance of compound eyes. [12] [13]
Dipteran morphology differs in some significant ways from the broader morphology of insects. The Diptera is a very large and diverse order of mostly small to medium-sized insects. They have prominent compound eyes on a mobile head, and (at most) one pair of functional, membraneous wings, [1] which are attached to