Due to the need of survival, there are many "mathematicians" not only in the plant kingdom, but also in the vast animal kingdom. In order to adapt to the objective environment, conform to some mathematical laws or have some mathematical instinct, their mathematical talent often surprises scientists. For example, how do tigers and lions hunt in the dark? Why do cats curl up in a ball when they sleep? How do ants move food several times heavier than themselves? How does the white birch leaf weevil use mathematical knowledge to build its nest? Why do red-crowned cranes fly in formation? Tigers and lions are nocturnal animals. At night, the light is weak, but they can still go out to hunt. What is the reason? It turns out that the retina behind an animal's eyeball is composed of cylindrical or conical cells. Cylindrical cells are suitable for sensing objects in weak light, while conical cells are suitable for sensing objects in strong light.

In the retina of Nocturnal Animals, such as tigers and lions, cylindrical cells are dominant. At night, their eyes are the brightest and largest, with a diameter of 3 ~ 4 cm. So, although the light is very weak, we can see it clearly.

In winter, when cats sleep, they always try to shrink their bodies into spheres. Why? It turns out that there is a principle in mathematics that the surface area of a ball is the smallest among objects of the same volume. The body size of a cat is certain. In order to minimize the heat loss when sleeping in winter and keep the temperature in the body as little as possible, cats skillfully "use" this geometric attribute.

Ants are industrious and gregarious insects. A British man named Henston once did an experiment: cut a dead grasshopper into three pieces, the second piece is twice as big as the first piece, and the third piece is twice as big as the second piece. When ants organize labor to carry these foods, the latter group is about 1 times that of the former group, and it seems that they also know the law of geometric series.

Birch leaf curl weevil can make a cone-shaped "delivery room" from birch leaves. It bites birch leaves like this: when the female weevil starts to work, she first climbs to a place not far from the petiole, bites through the leaves with her sharp jaw, and retreats to bite out the first arc crack. Then climb to the other side of the leaf and bite out a curve with less curvature. Then go back to the beginning and roll the lower part of the leaf into a very thin cone and turn it for 5 ~ 7 times. Then roll the other half into a conical cylinder in the opposite direction, thus making a solid "delivery room".

The formation of red-crowned cranes is also mysterious. Red-crowned cranes fly in groups and form a "human" shape when migrating. It is observed that the angle of the herringbone is always 1 10, and the half angle of the herringbone is 54 44' 8 ",and the angle of the diamond crystal is the same.