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The eyespot apparatus (or stigma) is a photoreceptive organelle found in the flagellate or (motile) cells of green algae and other unicellular photosynthetic organisms such as euglenids. It allows the cells to sense light direction and intensity and respond to it, prompting the organism to either swim towards the light (positive phototaxis ...
Eyespot (mimicry), a color mark that looks somewhat like an eye; Eyespot, a sensory organ of invertebrates; see simple eye in invertebrates; Eyespot, a type of eye in some gastropods, a part of sensory organs of gastropods; Eyespot apparatus, a photoreceptive organelle found in the flagellate (motile) cells unicellular photosynthetic organisms
An eyespot (sometimes ocellus) is an eye-like marking. They are found in butterflies, reptiles, cats, birds and fish. Eyespots could be explained in at least three different ways. They may be a form of mimicry in which a spot on the body of an animal resembles an eye of a different animal, to deceive potential predator or prey species.
The apparent "eye color" in these animals is red or black. [4] Certain groups such as box jellyfish have more complex eyes, including some with a distinct retina, lens, and cornea. [5] Many snails and slugs also have ocelli, either at the tips or bases of their tentacles. [6] Some other gastropods, such as the Strombidae, have much more ...
The thin overgrowth of transparent cells over the eye's aperture, originally formed to prevent damage to the eyespot, allowed the segregated contents of the eye chamber to specialise into a transparent humour that optimised colour filtering, blocked harmful radiation, improved the eye's refractive index, and allowed functionality outside of water.
The eyespot is located near the cell equator. It is composed of a carotenoid -rich granule layer in the chloroplast which act like a light reflector. [ 6 ] The main function of the eyespot is the phototaxis , which consist of the movement (with the flagella ) related to a light stimulus. [ 7 ]
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 irises of human eyes exhibit a wide spectrum of colours. Eye color is a polygenic phenotypic trait determined by two factors: the pigmentation of the eye's iris [1] [2] and the frequency-dependence of the scattering of light by the turbid medium in the stroma of the iris.