What's under the sea?

Divers have seen famous large marine animals such as shrimp, squid, octopus, cuttlefish and sperm whale in thousands of meters deep sea water; Groups of anglerfish were found in the water depth of 2000 ~ 3000 meters: in the water layer below 8000 meters, a new species with a body size of only 18 cm was found. In the deepest part of the Mariana Trench, animals are rarely seen.

If people don't see these many deep-sea life forms with their own eyes and only listen to their rumors, they will think that this is a fantasy. Because, these seemingly very weak life, first of all, have to withstand the test of hundreds of atmospheres. Take the small fish that people see under more than 7000 meters of water. In fact, it has to withstand more than 700 atmospheres. In other words, this small fish has been under pressure of 700 kilograms in an area the size of our fingernails. This pressure can crush steel cans. Incredibly, deep-sea fish can swim freely as usual. In the deep sea of 10 thousand meters, people saw a few centimeters of small fish and shrimp. These small fish and shrimps are under pressure of nearly one ton. So much pressure, not to mention tanks, even things harder than tanks will be crushed.

However, why can deep-sea fish bear such great pressure on the seabed?

It turns out that the physiological function of deep-sea fish has changed greatly in order to adapt to the environment. These changes are reflected in the muscles and bones of deep-sea fish. Due to the huge water pressure in the deep sea environment, the bones of fish become very thin; But also easy to bend; Muscle tissue becomes particularly flexible and fiber tissue becomes surprisingly fine. More interestingly, the fish skin tissue becomes only a thin layer, which can make the physiological tissue in the fish full of water and keep the balance between internal and external pressure. This is why deep-sea fish will not be crushed to death under such great pressure.

A difficult transition

In addition, the eyes of deep-sea fish have become very strange. Our common goldfish not only has bright colors, but also has big eyes, which is very fun. Compared with goldfish, the eye structure of fish living in deep sea is much richer than goldfish. Generally, the eyes of fish are mostly on both sides of the head, while those of fish living in the deep sea are on the back of the head. Seen from the front, the fish's two big eye frames are like two upright light bulbs. From top to bottom, the eyes are like two big circles, occupying the "key" part of the head. More interestingly, this fish eye can move up and down, left and right, the eyeball structure is similar to a telescope, and the focal length can be adjusted freely. The peculiar eye structure is almost a physiological feature of deep-sea fish.

Deep sea killing

The deep sea is not calm, there is a lot of blood and killing. Now scientists have been looking for more than 10 overlord medals, which live at the bottom of the sea all the year round. So far, no one has seen its true face, but the natural enemy of Bawangzhang is the sperm whale. Scientists have found giant octopus teeth with a diameter of 20 cm in the abdomen of sperm whales. Scientists have concluded that this octopus is the overlord chapter. But the natural enemy of sperm whales is overlord, which means they have been killing blood in the deep sea.