Extended data

Cervidae belongs to the family Artiodactylidae. Some characteristics of Cervidae species are: the fur is gray, brown, reddish brown and yellow; There is a black exposed area on the snout (except reindeer); Most species have short tails, and elk has the longest tail. There are obvious black concave tear pits under the eyes; Each foot has four hooves, and the hooves are very small in shape.

Except for a few species, the canine teeth of most species degenerate or disappear; Male individuals have horns and female individuals have no horns (except reindeer females); Male antlers begin to shed at the end of the breeding season every year, and at the same time, they begin to grow new antlers. Entering the breeding period, the antlers are completely ossified.

According to the morphological characteristics of Cervidae, it can be divided into four subfamilies, among which the species of Cervinae are distributed in the American continent, and the species of Swertia, Cervinae and Muntjac are distributed in parts of Asia, Europe and Africa.

Cervidae animals are distributed in all kinds of grasslands, forests, even deserts and tundra. All deer feed on plants, and the larger species eat more kinds of plants. Leaves, stems, flowers and fruits of herbs, twigs, leaves and even branches and barks of woody plants are all on its "menu".

The reproductive system is one male and many females. Species living in temperate and cold temperate zones have obvious breeding periods, while species distributed in tropical and subtropical zones can breed all year round.

Among the 18 species of Cervidae distributed in China, 6 species (sika deer, deer with deer, white-lipped deer, elk and muntjac) are listed as national first-class protected wild animals, and the population of deer with deer with deer is the least, which is extremely endangered. Four species (red deer, water deer, moose and roe deer) are listed in the second-class protected wildlife list in China.

Horns are the second characteristic of stags (only reindeer Rangifer tarandus has horns for both sexes) and are also courtship weapons. Its growth and shedding are influenced by pituitary and testosterone. After the breeding season, the antlers in the north will fall off from Lower Mao Kou, and the next year they will be born from Mao Kou above the frontal bone 1 peduncle joint.

The newly grown horn is called velvet antler, which has skin and hair, and a large number of blood vessels supply blood, which is divided into branches; As the horn grows up, the blood supply gradually decreases and the skin dries out. When 1 ~ 2 years old, the initial angle is almost straight, and the bifurcation of the posterior angle increases year by year until adulthood.