Adult crocodiles are often underwater, with only their eyes and nose exposed. They have keen eyes and ears and will sink immediately when they are frightened. In the afternoon, I float in the sun, and at night, my eyes are bright. Crocodiles, like birds, circulate gas in one direction through their lungs, unlike mammals, where gas enters and exits through small liquid sacs. Gas enters from the trachea, passes through the lungs to the tail, and then is discharged from the nostrils through the trachea. This function enables crocodiles to absorb more oxygen through their lungs when needed than mammals.
Crocodiles are cold-blooded egg-laying animals. Crocodiles are extremely precious animals. Crocodiles are not fish, but reptiles and crocodiles, or they are named "crocodiles" because they play in water like fish. Crocodiles are one of the earliest and most primitive animals discovered so far. A fierce vertebrate reptile, which appeared in the Mesozoic from Triassic to Cretaceous (about 200 million years ago). It was a carnivore as well as a dinosaur. There are 23 recognized crocodile species. Crocodiles domesticated and bred in China are: Chinese alligator, Siamese crocodile, Gulf crocodile and Nile crocodile; Among them, there are three kinds of crocodiles allowed to be operated and utilized by the state: Siamese crocodile, Gulf crocodile and Nile crocodile. Among them, the Siamese crocodile (also known as Thai crocodile) is widely domesticated in northern China. The unit issuing the crocodile domestication and breeding certificate is: State Forestry Administration.