Search results
Results from the WOW.Com Content Network
In vertebrate eyes, the nerve fibers route before the retina, blocking some light and creating a blind spot where the fibers pass through the retina. In cephalopod eyes, the nerve fibers route behind the retina, and do not block light or disrupt the retina. 1 is the retina and 2 the nerve fibers. 3 is the optic nerve. 4 is the vertebrate blind ...
Although color changes appear to rely primarily on vision input, there is evidence that skin cells, specifically chromatophores, can detect light and adjust to light conditions independently of the eyes. [34] The octopus changes skin color and texture during quiet and active sleep cycles. [35]
An octopus ( pl.: octopuses or octopodes[ a]) is a soft-bodied, eight-limbed mollusc of the order Octopoda ( / ɒkˈtɒpədə /, ok-TOP-ə-də[ 3] ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefish, and nautiloids. Like other cephalopods, an octopus is bilaterally symmetric with two ...
Compound eye. A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, [ 1] which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distinguish brightness and color. The image perceived by this arthropod eye is a ...
History of research. The human eye, showing the iris and pupil. In 1802, philosopher William Paley called it a miracle of " design ." In 1859, Charles Darwin himself wrote in his Origin of Species, that the evolution of the eye by natural selection seemed at first glance "absurd in the highest possible degree". [ 3]
Simple eye in invertebrates. A simple eye or ocellus (sometimes called a pigment pit[ 1][ 2]) is a form of eye or an optical arrangement which has a single lens without the sort of elaborate retina that occurs in most vertebrates. These eyes are called "simple" to distinguish them from "compound eyes", which have multiple lenses.
Diagram of a human eye; note that not all eyes have the same anatomy as a human eye. The mammalian eye can also be divided into two main segments: the anterior segment and the posterior segment. [10] The human eye is not a plain sphere but is like two spheres combined, a smaller, more sharply curved one and a larger lesser curved sphere.
[10] Octopus eyes, too, look and work much like those of vertebrates; but there, Baer remarks, the similarities end. Cephalopods are "immensely foreign", with "a distributed sense of self" and a "lived reality" quite unlike human consciousness, a feature that, he notes, Godfrey-Smith calls "the most difficult aspect of octopus experience to ...