2021-04-14
It is known, the ancient ancestors of domestic dogs were wolves: ravenous and active at any time. Wolves have a wonderful instinct that helps them track prey on the trail. Also, they have a unique vision, which helps them to see prey from a distance, especially when it moves. Vision is of particular importance during the final jump and throw.
Large eyes, almost human's. Another interesting fact is that the breeds are different, but the eye size is the same. For this reason, small dog breeds are funny, for example, Chihuahuas, look "pop-eyed".
Location of the eyes provides dogs with a broad overview of the side, approximately 250 - 270 degrees. The objects located ahead, they see as people, with two eyes. The binocular vision angle is about ninety degrees, and it is significantly less than the owner of the dog has. Nevertheless, it is enough the dog can correctly estimate the distance to the thrown ball, stick, or to prey.
What is the difference between a human's and a dog's vision? Dogs qualitatively see objects in the darkness, since their retina, as well as human's, has two types of light-sensitive receptors "rods", which provide a clear image with a variety of light; and "cones", which provide color vision, and only in bright light. Dogs have two times more "cones" than humans do.
The dog has in the eyeball a light-reflecting layer called the tapetum. Through this layer, a beam of light falls on the retina of the eye twice and thus doubles the amount of light. It is because of the tapetum, the dog's eyes flash in the dark and are light yellow. They lit when the flashlight is on them.
Color perception of dogs is not as rich and varied as humans. Previously, just fifteen years ago, it was believed that all dogs live in a bleak, gray world.
So, if you compare the vision of man and dog, then:
Humans have three types of "cones", which are responsive to such colors - blue, red, and green.
Dogs have only two types of "cones" and it sees all colors except orange, yellow, and red.
Everyone who played with the dog in the ball or threw them a stick or a "Frisbee" surely noticed how cleverly the dog catches them! As if anticipating where the ball will fly! Not everyone is capable of that! What is the secret?
The secret lies in a special structure of the dog's eyes. Or rather, in the receptors - "rods", located in the retina. For comparison, a human can perceive sixty consecutive images per second. It is called flicker fusion frequency. In our furry friends, this frequency reaches eighty images per second. During a fraction of a second, they may notice more than a man, in this case, not only observing but also reacting! One can only imagine what goalkeeper dogs would be like! Once upon a time, people believed that wolves were afraid of pennants' red color. No. They are afraid of the fact there are unfamiliar smells and objects on their territory. Pennants can be very different if only differed in the snow.
