Walruses have a thick layer of subcutaneous fat to resist the extremely cold sea water in the Arctic Circle. When walruses stay in cold seawater, the capillaries in their bodies contract and blood can only flow under the fat layer. At this time, the fat layer looks like a white "cotton-padded jacket", so the walrus' skin looks white.

This cotton-padded jacket keeps walrus warm. However, once walrus surfaced, if the weather gets warmer in summer, its capillaries will expand rapidly and its skin will look deep and red.

Demographic status:

Walruses are also particularly sensitive to changes in the marine environment. Due to the large-scale exploitation of oil and natural gas, many walruses' habitats are polluted, so that they cannot survive and become extinct, and their distribution area is gradually shrinking.

With the increasing demand for sea ivory, the walrus hunting industry is also developing, and the hunting tools and methods are constantly improved and perfected, which has caused a devastating blow to the living conditions of walrus, and the population has dropped sharply, from several million two or three centuries ago to less than 70,000.