• previous unit
• unit index
• next unit

• full read
• en español
• print

A Little Bit More

As the poster points out, a snake’s ability to expand its skull, is the key to its swallowing food larger than its head. A snake’s lower jaw also comes in to play in the swallowing process, not just the skull. Its lower jaw, which is connected by a stretchy ligament at the front of the jaws, allows them to pull widely apart while the middle of each lower jaw has a joint that can bow outward with large meals to further improve its accommodation. The bones of the upper jaw are much more flexible than most animals and this allows the snake to kind of “walk” its jaw, side to side, up the animal’s body as it slides the prey deeper into the snake’s throat. Maybe not very pretty, but very effective!

You may wonder how a snake can have a mouth and throat completely full of food and breathe at the same time – you can’t do that! A snake is able to move the end of its trachea (windpipe) to the side so it can breathe even as it swallows large prey that may take an hour or more to accomplish.

Snakes are ectotherms (cold-blooded) but can speed up the digestive process by moving to a warm location after a meal. Snakes regularly find a warm, sunny location to rest after feeding where their meal can be digested. The best digestive temperature for snakes is about 30C (86F) but if their body temperature falls below 10C (50F) after a meal, a snake will regurgitate its food rather than allow it to decay within its body. Too often, snakes find a highway to be good sunning location, often with disastrous results.

Activities

Sock Walk

In the text, we discuss how a snake actually uses its jaws to “walk” over its prey. This may not be too clear for most people to think about if they’ve never seen it occur in nature but in reality, they do something similar all the time. Each time one slips a tight fitting sock or wet swimsuit onto their body, they do something very similar. Have your students try this:

1. Have each student remove one shoe and sock from either foot

2. Have each student place the bare foot heel down on the floor and keep that heel immobile throughout the exercise

3. Now have each student place their sock near their toes and using only ONE hand (no fair using two!), pull their sock onto their foot. Keep in mind that the student’s heel must remain stationary and not lift above the floor. Once their toes are completely into the end of the sock, they can lift their heel and pull the sock completely on.

Very quickly it should be apparent to the students that to do this exercise, they need to “walk” their sock up onto their foot, one side at a time much as a snake does when swallowing its prey. Granted, it’s not the same but this should help them get the idea.

Key Concepts

Structures and Functions, Predator/Prey Relationships

Questions

Do you have a question for a naturalist? Go ahead and ask!

It's easy -- just fill out this form, submit your question and you'll receive an answer shortly.