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The rate of eye evolution is difficult to estimate because the fossil record, particularly of the lower Cambrian, is poor. How fast a circular patch of photoreceptor cells can evolve into a fully functional vertebrate eye has been estimated based on rates of mutation, relative advantage to the organism, and natural selection.
The example on the left is the image of an eye of a vertebrate. On the right, that of an octopus. 1: Retina 2: Nerve fibers 3: Optic nerve. 4: Blind spot: Date: 1 September 2008: Source: Own Work, based on Image:Evolution_eye.png created by Jerry Crimson Mann 07:07, 2 August 2005 UTC (itself under GFDL). Author: Caerbannog: Other versions ...
They have difficulty differentiating between red and green, [40] and much like other mammals, the dog's eye is composed of two types of cone cells compared to the human's three. The divergence of the eye axis of dogs ranges from 12 to 25°, depending on the breed, which can have different retina configurations.
dachshund (dac) is a gene involved in the development of the arthropod compound eye [1] which also plays a role in leg development. [2] It is activated by the Distal-less (Dll) gene. [ 3 ]
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Dogs have ear mobility that allows them to rapidly pinpoint the exact location of a sound. Eighteen or more muscles can tilt, rotate, raise, or lower a dog's ear. A dog can identify a sound's location much faster than a human can, as well as hear sounds at four times the distance. [41] Dogs can lose their hearing from age or an ear infection. [42]