Another trick of the eye that parrots have over us is that they can rapidly dilate and constrict their pupils at will, a behavior known as pinning, which they do when they are excited or feeling aggressive. The object will be in vivid color, however: parrots can see the same red, blue, and green light that humans can, but they can also see ultraviolet and fluorescent light, which we cannot. That’s why when a parrot is intently looking at something, it turns its head or body sideways and focuses one eye on the subject, using monocular vision. In Vivid ColorĪ parrot’s eyes are located toward the sides of its head, which gives it better lateral than frontal vision. In addition, the ommatidia in mantis eyes (as well as those of bees and dragonflies) are arranged specifically for acute vision and to receive more light, so they have better vision than some insects. The information is sent to the brain, which then integrates all the spots together to form an image. Compound eyes are made up of many individual units called ommatidia, and each one focuses a spot of light on the retina at its base. But unlike us, they have an insect’s intricately designed compound eyes, which masterfully detect movement and provide a wide angle of view. Like humans, mantises have binocular vision, which allows them to judge the distance to their prey before striking. These animals also have blind spots directly in front of their face and directly behind their back legs-if you startle them while standing behind them, you risk getting kicked. That’s why if you reach out to pet a goat’s head, it will often step back and look up at your hand-it can’t see what’s directly above it otherwise. Because of the horizontal pupil, they can’t look up or down without raising or lowering their head. That’s an important advantage for a prey species that needs to see what’s coming! There are some disadvantages, though. They can see pretty much all around themselves without having to move, and they can see better at night than we can. While some people find this look disconcerting, the pupil shape and position give these animals a panoramic visual range covering 320 to 340 degrees (human vision only covers about 180 degrees). Many hoofed animals, including goats, sheep, deer, antelope, horses, and cattle, have eyes placed on the sides of their head and have horizontal pupils, which are nearly rectangular when dilated. If you’re out in a forest at night and shine a flashlight, the glowing eyes peeking back at you are the result of this reflection, referred to as eyeshine. Also, like many other nocturnal species, the loris has a reflective layer behind the retina called the tapetum lucidum that reflects and intensifies whatever light is available. Nocturnal animals like the loris tend to have big eyes in proportion to their body size and pupils that open wide in low-light conditions-what may seem like pitch black to a human may look like dim light to a loris. NovemBY Karen Worley Photography by Ken Bohn The Better to See You (in the Dark) With
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