Why are animal eyes shining under the lights

Wolves and many nocturnal animals have eyes glowing under the lights. ( Photo: Inspirationline ) The human eye also reflects light, as every photographer knows . but just not very good. In some photos our eyes also turn red. But it is not a reflector. That's because the light from the camera bounces off the red blood vessels and the red muscle behind the retina.

The characteristic shining eyes of wolves, North American pandas, crocodiles and many other species, were born from "tapetum lucidum" - a cell layer that acts like a mirror behind the retina. This structure is present in most nocturnal animals, acting as a light amplifier. Often, the retina captures part of the light that hits the eye, but lets another part pass through. The tapetum lucidum mirror will reflect this pass through the retina, giving the animal a chance to "see" it a second time.

It is this light that bounces back to enchant horror stories for superstitious people.

What about the ability of people to see in the dark? Cats adapt better than us in low light conditions. They have a larger cornea and pupil of humans, so getting more light in a dim state. They also have a tapetum mirror that helps reflect light back to the eye. In this way, their retina has two opportunities to access the same photon of light. Tapetum of cat's eyes reflects light 130 times, stronger than human eyes. That's why the cat's eyes glow in the dark on the photos.

You can argue that people are not the animals that look in the dark, but we must have the best day vision. About this, we are far behind the eagle. Eagle eyes have the same size and weight as human eyes. But they have a different shape. The back (back) of their eyes is flatter and wider than the back of our eyes, giving it a much larger field of view.

The back of the human eye has a special area in the retina called fovea - where many of the light-receiving cells are concentrated. Fovea's people have about 200,000 cone cells per millimeter, a number so big that you can hardly imagine. But it has not been absorbed in comparison with the eagle. Their fovea has about 1 million cones per millimeter. It allowed the eagle to see a mouse 1.6 km away. That is beyond human ability.

Thuan An