We now know that cat’s eyes appear to glow because they, along with the eyes of many other nocturnal animals, reflect light. All eyes reflect light, but some eyes have a special reflective structure called a tapetum lucidum that create the appearance of glowing at night.
Other animals’ eyes glow too
Many other animals that need to see at night have a tapetum lucidum. That includes predators and prey alike, everything from wild foxes to farmed sheep and goats.
The tapetum lucidum is also useful to fish, dolphins and other aquatic animals, because it helps them see better in murky, dark water.
In land animals, the tapetum is found in the top half of the eye behind the retina, because they need to see what is on the ground best. But in aquatic animals the tapetum takes up most of the eye, because they need to see all around them in the dark.
Like cats, the lemur, a small primate, and its close relative, the bush baby – also known as a “night monkey” – also have a superreflective tapetum made with riboflavin.
Even though a lot of animals have eyeshine, some small domesticated dogs lack this trait. Most animals with blue eyes and white or light-colored coats have also lost this trait.
So don’t be alarmed if your dog’s or cat’s eyes don’t glow. The list of other species without a tapetum lucidum includes pigs, birds, reptiles and most rodents and primates – including humans.
Species whose eyes glow have evolved to see better in low light because they either forage or need to look out for predators throughout the night, or they do most of their hunting at dawn and dusk. In fact, domesticated cats can see in conditions that are only 16 percent as bright as what people require. Read the full article on The Conversation. The article was translated into Bahasa Indonesia.
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For The Conversation’s Curious Kids, Braidee Foote, a clinical assistant professor in the University of Tennessee, Knoxville’s College of Veterinary Medicine, recently provided an explanation on why cats’ eyes glow.
Many animals, including most dogs and cats, have the ability to reflect light from their eyes. This explains why cats’ eyes typically glow in the dark or shine brightly in pictures taken in poorly lit areas. They may also glow when lit by a flashlight or a car’s headlights.
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