World Giraffe Day丨How much do you know about the tallest mammal on land?

June 21st is World Giraffe Day.

Giraffes are the tallest mammals on land! Their four long legs alone are taller than many humans, at about 1.8 meters. Long legs don't mean they run slowly. In short distances, giraffes can reach speeds of 35 kilometers per hour!

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How much do you know about giraffes?

The giraffe is a ruminant even-toed ungulate living in Africa and the tallest extant land animal in the world. When standing, a giraffe can be 6 to 8 meters from head to toe and weigh about 700 kilograms. A newborn baby is 1.5 meters tall.

The Latin name of giraffe means "camel with leopard prints". In people's eyes, every giraffe seems to be the same. But in fact, the patterns on each giraffe are unique. It can be said that the patterns on each giraffe are unique, just like human fingerprints. A young giraffe can recognize its mother by the patterns on its body.

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Giraffes live in arid and open savannahs and like to live in groups. The number of giraffes in a group varies greatly, from 2 or 3 to more than 40, sometimes up to more than 70. Their food is leaves and branches of various tall trees. They spend most of the day eating, especially in the morning and afternoon, when they are almost always eating. Because of their long legs and necks, they can reach leaves 6 meters above the ground.

Did China once have giraffes?

According to fossil records, the ancestor of early giraffes, Canthumeryx, first appeared in North Africa 25 million years ago. By 14 million years ago, giraffes were living throughout Eurasia and Africa.

By 9 million years ago, Giraffe, whose appearance was very similar to that of modern giraffes, entered present-day China and northern India, and evolved into the genus Giraffe in this area, entering Africa again around 7 million years ago.

Due to climate reasons, all giraffes in Asia became extinct, while giraffes in Africa survived and evolved into several new species. Modern giraffes appeared in East Africa during the Pleistocene (1 million years ago).

Competition for mates or feeding pressure?

This is why giraffes' necks are getting longer

Why do giraffes have such long necks? This is a key topic in evolutionary biology. To explain this problem, biologist Lamarck proposed the theory of use and disuse; Darwin proposed the theory of natural selection.

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Long necks are obviously the most representative feature of giraffes. Such long necks also make it difficult for them to drink water. In the past, people mainly believed that their long necks were used to eat leaves from high places, but a study published in Science earlier this month disagreed. Researchers from the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences and other institutions found that the courtship competition between male Xiezhi disc-horned deer promoted the evolution of their cervical vertebrae in the direction of becoming thicker; at the same time, the results also support the view that courtship competition between male giraffes directly promoted the lengthening of giraffe necks. Environmental changes and natural selection pressures from feeding are more likely to be a potential background.

Although giraffes do not have ivory or rhino horns, many people believe that their brains and spinal cords can be used to treat diseases, their skins can be used to make fur products, and some poachers even kill giraffes simply for their meat.

In the past 30 years, the number of giraffes has decreased by 40%, and the current number of wild giraffes is estimated to be less than 98,000. The IUCN Red List of Threatened Species has listed giraffes as "vulnerable".

Let us take care of our “long-necked friends” together!

Comprehensive sources: Science and Technology Daily, Beijing Zoo's official science public account, WWF World Wildlife Fund's official Weibo, etc.