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The term "ocellus" (plural ocelli) is derived from the Latin oculus (eye), and literally means "little eye". In insects, two distinct ocellus types exist: [9] dorsal (top-most) ocelli, and lateral ocelli (often referred to as ocelli and stemmata, respectively), most insects have dorsal ocelli while stemmata are found in the larvae of some ...
Ocelli (the plural of ocellus) are a type of simple eye, or eyespot. They are photoreceptive, but very simple; differing from complex eyes with compound lenses, ocelli cannot morph the sensation of light into a complete image, and are utilized to sense movement and the absence and presence of light.
The ocelli are in an otd-rich area and disruption of otd results in loss of the ocelli, but does not affect the compound eyes. [10] Inversely, the transcription factor dachshund (dac) is required for the patterning of compound eyes, but mutants lacking dac do not exhibit loss of the ocelli. [11] Different opsins are used in the ocelli of ...
[11] [21] The ocelli are not homologous to the simple eyes of caterpillars which are differently named as stemmata. [5] The ocelli of Lepidoptera are reduced externally in some families; where present, they are unfocussed, unlike stemmata of larvae which are fully focussed. The utility of ocelli is not understood at present. [5]
Some reptiles, such as the sand lizard of Europe, have eyespots; in the sand lizard's case, there is a row of spots along the back, and a row on each side. [12]Many species of cat, including Geoffroy's cats, jungle cats, pampas cats, and servals, have white markings, whether spots or bars, on the backs of their ears; it is possible that these signal "follow me" to the young of the species.
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.
The Tabaninae lack ocelli (simple eyes) and have no spurs on the tips of their hind tibiae. In the Pangoniinae, ocelli are present and the antennal flagellum (whip-like structure) usually has eight annuli (or rings). In the Chrysopsinae, the antennal flagellum has a basal plate and the flagellum has four annuli.
The ocelli, when present, are located in the top of the head, arranged at the corners of a triangle in an area called stemmaticum or ocellar triangle. For the purpose of systematics, the presence, the arrangement, and the conformation of the cephalic bristles is important and they have a specific terminology.