Walrus is a carnivorous mammal living in the sea, belonging to the order Pinpoda. Its body is cylindrical, its skin is thick and wrinkled, its head is flat and forward, its face is covered with a beard as hard as a brush, and it has four fleshy and flexible flippers. Two hind flippers can bend forward, and a pair of small eyes are buried in skin folds.

The most prominent feature of walrus is that it has a pair of long teeth on the maxilla, protruding from two corners of the mouth. Adult walruses, both male and female, have tusks, each of which can reach 70-80 cm and weigh more than 4 kg.

What is the function of walrus' tusks? Some people say that tusks are tools for walruses to climb towering ice floes or cliffs, weapons to fight opponents, and also used to break the unstable ice. But these are secondary, and the most important use of its tusks is to dig the seabed to get food. So walruses are called "underwater cultivators" by some marine biologists.

Walrus is a mammal that breathes with its lungs, so before it dives into the sea to dig the bottom of the sea, it must stretch its breath on the water, let its lungs breathe in enough fresh air, dive vertically into the bottom of the sea, and then start to turn over the ground. Walrus is very distinctive. After the whole tooth is inserted into the soil, it either moves its neck in situ or pushes forward. Sometimes it looks like shoveling, and sometimes it looks like plowing with cattle. When they open the soil layer with their tusks, the sediment clouds will rise around them. After walrus plowed for two or three meters or more on the seabed, clams and other foods were dug out of the soil. It collected the food together with its flexible forelimbs, which also contained a lot of soil. Walruses float on the surface of Shanghai with food, rubbing their fins back and forth and rubbing shells to pieces. Then the walrus released his "hand", and the broken shell separated from the meat and raced to sink to the bottom of the sea. The peeled clean meat slowly sinks, and walruses will return to the sea to catch meat to eat. When it has a full meal, it will dive out of the water and let its lungs breathe fresh air.

Walrus teeth are very precious. Besides carving, ivory can also be processed into various products. For example, as early as the Middle Ages, the powder ground from ivory was a very important medicinal material, and it could also be made into decorations such as knives and daggers.