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Watch the Video. Click here to watch on YouTube. Few people have spent time gazing into a sheep’s eyes, but if you have, you may have noticed something very strange about their pupils. Instead ...
Nocturnal animals (for example, tarsiers) and animals that live in open landscapes have larger eyes. The vision of forest animals is not so sharp, and in burrowing underground species (moles, gophers, zokors), eyes are reduced to a greater extent, in some cases (marsupial moles, mole rats, blind mole), they are even covered by a skin membrane.
Some skates and rays have crescent shaped pupils, [17] gecko pupils range from circular, to a slit, to a series of pinholes, [18] and the cuttlefish pupil is a smoothly curving W shape. Although human pupils are normally circular, abnormalities like colobomas can result in unusual pupil shapes, such as teardrop, keyhole or oval pupil shapes.
Dichromatic vision is the result of the animal having two types of cones in their eyes: a short-wavelength-sensitive cone (S) that is optimal at 428 nm (blue), and a middle-to-long wavelength sensitive cone (M/L) which sees optimally at 539 nm, more of a yellowish color. [14]
The tapetum lucidum, in animals that have it, can produce eyeshine, for example as seen in cat eyes at night. Red-eye effect, a reflection of red blood vessels, appears in the eyes of humans and other animals that have no tapetum lucidum, hence no eyeshine, and rarely in animals that have a tapetum lucidum. The red-eye effect is a photographic ...
A slit pupil can indicate the common multifocal system, while a circular pupil usually specifies a monofocal system. When using a circular form, the pupil will constrict under bright light, increasing the f-number, and will dilate when dark in order to decrease the depth of focus. [49] Note that a focusing method is not a requirement.
The eye of a bird is larger compared to the size of the animal than for any other group of animals, although much of it is concealed in its skull. The ostrich has the largest eye of any land vertebrate, with an axial length of 50 mm (2.0 in), twice that of the human eye. [1] Bird eye size is broadly related to body mass.
Cephalopods, as active marine predators, possess sensory organs specialized for use in aquatic conditions. [1] They have a camera-type eye which consists of an iris, a circular lens, vitreous cavity (eye gel), pigment cells, and photoreceptor cells that translate light from the light-sensitive retina into nerve signals which travel along the optic nerve to the brain. [2]