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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 ...
They may be a form of self-mimicry, to draw a predator's attention away from the prey's most vulnerable body parts. Or they may serve to make the prey appear inedible or dangerous. Eyespot markings may play a role in intraspecies communication or courtship; a well-known example is the eyespots on a peacock's display feathers.
The outermost layer, known as the fibrous tunic, is composed of the cornea and sclera, which provide shape to the eye and support the deeper structures. The middle layer, known as the vascular tunic or uvea , consists of the choroid , ciliary body , pigmented epithelium and iris .
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.
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
Together with the leading flagellum, the eyespot allows the organism to move in response to light, often toward the light to assist in photosynthesis, [24] and to predict day and night, the primary function of circadian rhythms. Visual pigments are located in the brains of more complex organisms, and are thought to have a role in synchronising ...
The macula (/ˈmakjʊlə/) [1] or macula lutea is an oval-shaped pigmented area in the center of the retina of the human eye and in other animals. The macula in humans has a diameter of around 5.5 mm (0.22 in) and is subdivided into the umbo, foveola, foveal avascular zone, fovea, parafovea, and perifovea areas.
Eyespot, photoreceptor used to sense light direction and intensity; Contractile vacuole, regulates the quantity of water inside a cell; Ventral flagellum; Ventral root; Golgi apparatus; modifies proteins and sends them out of the cell; Endoplasmic reticulum, the transport network for molecules going to specific parts of the cell; Phagosome