Why can pythons eat food much bigger than their heads when eating?

There is a saying that "the snake swallows the elephant unintentionally", which is used to describe the insatiable human nature. Although "snake swallowing elephant" does not exist in nature, it vividly reflects the swallowing ability of snakes-most snakes can indeed swallow prey much wider than their heads and bodies.

However, most people's understanding of snake swallowing behavior may still come from popular science books or documentaries, and there are still many details worthy of further exploration and scrutiny. When I am engaged in snake research, I am often asked, "Why can snakes swallow prey much bigger than themselves?" This question.

Today, we will start with the bones of the snake, especially the skull, teeth and jaw joints, to explain the mechanism of snake swallowing prey, and further explore what is the biggest prey that the snake can swallow? Can you swallow people?

How many bones does a snake have?

Before figuring out this problem, we might as well look at the main part of the snake bone.

For live snakes, their bones are mainly divided into skull, vertebrae and ribs, among which vertebrae are divided into atlas, axis, cervical vertebra and coccyx. Snakes have no typical limbs, shoulder straps, belts and pelvis.

In fact, snakes do not absolutely have no "limbs", but in the process of evolution, their limbs gradually degenerate because they adapt to a special environment and lifestyle (such as digging holes in the soil).

Relatively dry snakes, such as pythons and tube snakes, have completely degenerated hind limbs. They have claw-like hind legs on both sides of the stomata at the back end of their bodies (that is, the tail roots). This "hind leg" has no athletic ability, but only plays an auxiliary role in grasping during mating.

Why can snakes swallow prey much bigger than themselves?

△ Complete skeleton specimen of Hannah snake esophagus, exhibited in zhejiang museum of natural history (production/Song Shijing Photography/Chen Yining)

△ The hind limbs of the ball python (see watermark for image source)

Because the limbs of snakes are highly degraded, tasks such as predation and swallowing mostly fall on their heads. Therefore, the skull structure of snakes is more complicated in vertebrates.

Among snakes, the skulls of most snakes contain 4 1 piece of hard bone (excluding atlas and axis). However, there are as many as 45 skulls in Boico and Boico (an extra pair of retroorbital bones and an extra pair of supraorbital bones).

△ Elaphe moellendorffi's skull model is scanned by CT, reconstructed and rendered by 3D, and its skull * * * contains 4 1 piece of hard bone (different colors represent different bone pieces).

Most of these bones can move independently or alternately under the traction of different muscles, cooperate with each other to bite prey and transport it to the digestive tract. So snakeheads are much more flexible than us-after all, adults only have 29 skulls, and only the upper and lower jaw joints can move freely.

Some researchers divide the skull into four parts: skull, snout, velopharyngeal organ, uvula and mandible, and some domestic documents also divide it into skull and pharynx.

Among them, the maxilla, dentate bone, palatal bone and pterygoid bone of snakes are mostly pointed and thin teeth (there are also teeth on the maxilla of Ranidae). So being bitten by a snake often leaves several rows of teeth marks.

After rendering the 3D CT reconstruction model of the bamboo locust skull, the order of the skull parts in the video is skull (light blue)-snout (yellow)-palate and jaw (green)-hanger and jaw (dark blue). (This is a moving picture, remember to replace it when it is released. )

Snakes have far more hindquarters than other vertebrates, ranging from one hundred to two or three hundred. Generally speaking, the thinner a snake is, the more vertebrae it has. A short and thick snake like a poisonous snake generally has only 100 vertebrae; Many walking snakes have more than 200 vertebrae, such as the white-striped golden snake. Snakes generally have dozens of coccygeal vertebrae-as few as twenty or thirty, and as many as seventy or eighty. The more snakes are good at climbing and scurrying, the longer their tails are, and the more tail vertebrae there are, such as Shudu snake and Zaocys. The tail of terrestrial or cave snakes is blunt, and the number of tail vertebrae is correspondingly small, such as sand python and second snake.