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Jul 18, 2005 · To see objects in low light levels, owl monkeys have evolved large eyeballs, their lenses have a more spherical shape than is seen in diurnal primates, and there are also more rods and fewer cones (Noback 1975). Though they do see in color, owl monkeys have less acute color vision than other primates.
Night monkeys, also known as owl monkeys or douroucoulis[2] (/ duːruːˈkuːliz /), are nocturnal New World monkeys of the genus Aotus, the only member of the family Aotidae (/ eɪˈɒtɪdiː /).
Mar 13, 2024 · The standout feature of these owl monkeys is their unusually large eyes, which evolved in response to a nocturnal lifestyle – they are the only new world monkeys to be active at night.
May 21, 2009 · Owl monkeys have relatively few cone cells, which are responsible for colour vision and fewer ganglion cells, which process the signals from the cones.
At the other extreme, the nocturnal owl monkeys are monochromatic (literally "one color"). They see only black, white, and intermediate grays. A rare genetic disorder in humans known as achromatopsia causes a similar inability to see colors due to defective cones.
Night monkeys have very large eyes and use their sense of vision extensively. They have excellent vision in low light and can see in color. They communicate with vocalizations and with chemical cues. A captive night monkey was reported to use as many as 50 different kinds of vocalizations.
Night monkeys are also called owl monkeys because of their round, flat face and eyes that resemble those of an owl. Night monkeys have a thick, woolly fur that ranges in color from gray to brown, with yellow to orange undersides.
