Sharks are sensitive to water temperature. When the water temperature is below 20℃, they will lack vitality. Sharks are generally distributed in tropical and temperate waters on the earth, and only a few species such as Greenland sharks live in cold waters. Not all sharks live in the sea, but some kinds of sharks live in fresh water, such as aggressive bull sharks.

Most sharks feed on marine animals such as fish. Sharks feed on injured marine mammals, fish and carrion, and destroy weaker members of animals.

Extended data:

1. Sharks are a kind of creatures in the ocean, and they are also in a dominant position in the marine biological chain. Sharks have a long history on earth. They existed on the earth about 300 million years before dinosaurs appeared, and have a history of more than 500 million years.

2. Shark embryos can feel danger approaching;

Shark embryos can also feel the potential danger nearby. For sharks, the most dangerous time is in the egg sac. With the gradual growth of shark embryos, the seal of oocysts begins to open, and predators can detect developing young sharks through electric fields. When the predator approaches the oocyst, the shark embryo can sense the danger, seal the mouth of the oocyst, and even stop breathing to avoid being discovered by the predator.

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