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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.
[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]
Ocelli are present; the fourth tarsal segment is cylinder-shaped. The four large wings are translucent, smoky grey, or mixed, and the anterior pair is slightly longer than the posterior one. Their aquatic larvae are used as fish bait and are called hellgrammites.
Each feather consists of a central shaft, loose barbs on its sides, and an ocelli or “eyespot” pattern at the end. The overall effect is an iridescent pattern of golds, greens, browns, and ...
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.
Ocelli obsolescent, but when present as mere minute dots their arrangement on the hind wing is as in the wet-season form. Antennae, head, thorax and abdomen brown; antennae sometimes cinereous white on the sides with the apex black. Male sex-marks in form 2, but that on the underside of the fore wing small (about 2 into, long) and black. [3]
Arthropods use combinations of compound eyes and pigment-pit ocelli for vision. In most species, the ocelli can only detect the direction from which light is coming, and the compound eyes are the main source of information, but the main eyes of spiders are ocelli that can form images and, in a few cases, can swivel to track prey.