In the cold waters of the North Pacific, there is a smart and lovely animal. They look very much like rats, but they have nothing to do with mice. Their fur is soft and beautiful. They share a common ancestor with minks. They only began to live in the sea about 10000 years ago. This animal is the sea otter.
The sea otter is about 1.5 meters long and weighs 40 kilograms. Behind it is a wide and flat tail more than 30 centimeters long. Sea otter has a small head but a strong body. It belongs to the smallest species of marine mammals. Sea otters are very flexible in the water. They even often swim upward on the water. If you look closely, you will find that they still carry a stone. What is sea otter doing? Do they use stones as weapons to fight against animals that try to hurt them at any time?
Of course not. Sea otters are marine animals. Most of their food is shellfish, abalone, sea urchins, crabs, etc. growing on the seabed. Occasionally, they catch a few fish to improve their taste. However, the sea otter's favorite food is sea urchin, but sea urchin has a hard shell and can't be opened by teeth alone. What can I do?
The sea otter came up with a very clever way: take a stone with him. Sea otters have flexible forelimbs and can easily hold food. When they want to eat sea urchins, they first lie on the water with their bodies backstroking. At this time, their abdomen is their dining table. It put the stone it carried on its belly, and then hit the sea urchin hard on the stone. Once it found that the shell was broken, the sea otter immediately sucked out the meat part inside, and threw the shell back to the sea. Not only sea urchins, but also shellfish that are difficult to start with, sea otters will draw gourds and open their tightly closed shells by knocking.
It is not easy to find a suitable stone, so after eating, the sea otter will save the stone for reuse next time.
According to statistics, sea otters are one of the most voracious animals on earth. They generally consume as much as 1 / 3 of their body weight a day. In other words, a 40 kg adult eats 10-15 kg of food a day. The fur of sea otter is very dense, about 125000 per square centimeter, twice as dense as mink, so it can be called the king of animal skin. Therefore, people have competed to hunt, resulting in a sharp decline in their number.