The "beard" that Shekou often stretches is actually a snake's slender and deeply forked tongue. The snake's tongue often sticks out from the notch of the kiss scale and keeps flashing. It collects chemical molecules in the air, adheres to or dissolves on the wet surface of the tongue, and then sends them to the nose hoe to produce a sense of smell.

The nose hoe is the olfactory organ of the snake, which is located in the deep recess in front of the palatine bone and opens in front of the top of the mouth. Its surface is covered with olfactory epithelium, and olfactory nerves are usually connected to the brain. Because it is not directly connected with the outside world, the tongue has become a necessary assistant for it to complete its olfactory function. The olfactory function of snake nose hoe is particularly developed, but the olfactory function of nasal cavity has become secondary.

Extended data:

In the absence of food, the metabolic frequency of snakes can be reduced by as much as 70%, which makes them not only die without eating or drinking for a long time, but also grow bigger.

Marshall McQueen, a graduate student in biology at Arkansas State University, found that snakes can grow longer even without food. McQueen believes that in the process of evolution, snakes gradually developed the ability to make efficient use of limited energy in the body.

Living in an environment where a large number of rodent prey can be caught, protein will convert more energy needed by the body than rattlesnakes and ball pythons. McQueen explained: "It may be more difficult to adapt to hunger by breaking down the snake that powered protein during the hunger period."

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