The sperm whale

Sperm whales are marine mammals belonging to the order Cetiformes and family Spermatidae. With a body length of up to 18 meters and a weight of over 50 tons, it is the largest toothed whale, with its head occupying one-third of its body. The head is huge, the lower jaw is small, and only the lower jaw has teeth. No dorsal fin; Highly capable of diving, it is the mammal with the deepest and longest diving time. Like a fish in size, it breathes through its lungs. Short neck, the head seems to be connected to the torso; Cervical spine healing; The nostrils are spray holes located at the snout end, the forelimbs become fins, the forearms degenerate, the palms become longer, and the number of toes increases, but the toes and claws cannot be seen from the outside; Hind limb degeneration; The tail is like a fish, with horizontal tail fins, and it swings by the tail when swimming.