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The evolution of spiders' eyes has received little attention, and as such not much is known on the subject. The principal and secondary eyes likely evolved separately, with the principal eyes being homologous to the ocelli of insects but the secondary eyes being derived from compound eyes.
The evolution of color vision in primates is highly unusual compared to most eutherian mammals. A remote vertebrate ancestor of primates possessed tetrachromacy , [ 1 ] but nocturnal , warm-blooded , mammalian ancestors lost two of four cones in the retina at the time of dinosaurs .
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]
Sometimes the needs for visual acuity in different functions conflict, and different parts of the eyes may be adapted to separate functions; for example, the Gyrinidae spend most of their adult lives on the surface of water, and have their two compound eyes split into four halves, two for underwater vision and two for vision in air. Again ...
A spider web preserved in amber, thought to be 110 million years old, shows evidence of a perfect "orb" web, the most famous, circular kind one thinks of when imagining spider webs. An examination of the drift of those genes thought to be used to produce the web-spinning behavior suggests that orb spinning was in an advanced state as many as ...
Evolution of color vision in primates; S. Spider vision; T. Vision in toads This page was last edited on 15 September 2013, at 02:57 (UTC ...
This week sees the addition of new Spider-Men, Aliens and Predators, and a new Star Wars: Visions comic. ... Spiders, Visions, Aliens, and Predators. Oliver Brandt. February 19, 2024 at 12:08 PM ...
The snake detection theory, [1] [2] [3] also sometimes called the snake detection hypothesis, suggests that snakes have contributed to the evolution of primates' visual system. According to the theory, predatory pressure from snakes has selected individuals who are better able to recognize them, improving their survival chances and therefore ...