Whales are not fish, they are mammals living in the sea. Whales are typical aquatic animals. Their bodies are streamlined like fish, so they are often called whales.

Seen from the side, the whale is round, slightly barrel-shaped and streamlined. Most kinds of cervical vertebrae are healed, and the head is directly connected with the body. It is impossible to twist the head without moving the body. The forelimbs are specialized into flippers with phalanges left inside. The hind limbs completely degenerated, leaving only 1 pair of small bone fragments. The rear part of the trunk is a tail handle, and the left and right ends of the tail end are opened to form a horizontal tail fin, which can swing up and down to push the body forward.

Cetaceans Most cetaceans have dorsal fins, which are located at the back or center of the back. Small eyes, no transient membrane and lacrimal gland, poor vision. There are no auricles, only tiny ear holes, but they can hear well in water and air. The external nostril is located on the top of the head, and all whales except freshwater dolphins have 1 layer of fat to keep warm, reduce the specific gravity of the body, increase buoyancy, and help to swim and breathe. The trachea and esophagus are completely separated, so you can't breathe through your mouth.

Extended data:

Whales use sonar much less frequently than dolphins and have a much longer range of activities. The sensitivity of dolphin sonar is very high. It can find metal wire with a diameter of 0.2 mm and nylon rope with a diameter of 1 mm several meters away, and it can distinguish only 200? ps？ Two signals can find fish hundreds of meters away, blindfolded, and walk through the pool full of bamboo poles flexibly and quickly without touching.

Dolphin sonar has a strong "target recognition" ability, which can not only identify different fish and distinguish different materials such as brass, aluminum, bakelite and plastic, but also distinguish the echo of its own voice from the sound waves played back by the person who recorded its voice. The anti-jamming ability of dolphin sonar is also amazing. If there is noise interference, it will increase the call intensity over the noise so that its judgment will not be affected.

Dolphin sonar also has the ability to express feelings It has been proved that dolphins are animals with "language" and "speak" through sonar system. Their sonar system has a clear division of labor, which is used for positioning, communication and alarm respectively, and has the special function of frequency modulation and phase modulation.