Ask A Scientist

How does a snake move?

Asked by: R.J. Stevens
School: Glenwood Elementary School, Vestal
Grade: 1
Teacher: Miss Herzog
Hobbies/Interests: Playing with iPod
Career Interest: Robot inventor

Answer from Dylan Horvath

Steward of Natural Areas

Research area: Wildlife biology/ecology-wolverines, bats, salamanders and birds.
Interests/hobbies: Drawing, photography, singing and hiking.
Web page address: http://naturepreserve.binghamton.edu

   

The ability of snakes to move without legs is one of the main reasons so many people fear snakes, but for me, it’s an example of the wonderful variety of life on this planet.  ‘Leglessness’ doesn’t make snakes inferior either; it’s just another way to survive.  Scientific knowledge of how snakes move is not fully complete and is important for biological and robotics applications.

Snakes are able to move in different ways depending on the situation.  In fact, some Asian tree snake species are able to glide through the air from one tree to another. Most snake methods of locomotion are combinations of two or more of the characteristics of muscle contraction, lateral ‘pushing’ on objects, varying weight distribution, and directional friction. Scientists have classified at least four main methods of locomotion for named lateral undulation, rectilinear, concertina, and sidewinding.  Different species may rely on one type of movement most of the time, but most snakes are capable of all of them.

Lateral undulation (or serpentine) is the most common form of movement in most species of snakes including the ubiquitous Garter Snake here in the U.S. Terrestrial (land) snakes and sea snakes swim with this motion as well.  A snake will flex its muscles to produce alternating waves down its body that push on objects such as rocks.  If you were to lie on your stomach and alternately move your hips, legs, and head side to side and somehow move forward, then you’d be doing lateral undulation.  Of course, it would be difficult for you to move forward because you don’t have one thing that’s essential for snakes; their belly scales.  The rough back edges of their belly scales allow for directional friction.

The second common mode of locomotion for snakes is rectilinear, the main method for large, heavy boas and pythons.  It’s a way for snakes to move very straight through a series of muscle contractions that push the belly scales against the ground.

Another method of snake movement is called Concertina, which is named after the type of instruments to which accordions belong.  The snake anchors its back end and pushes the front of its body forward and then anchors the front to pull up the back half.  This method allows snakes to move slowly and carefully when stalking prey or climbing trees.

Finally, snakes when moving on surfaces that don’t provide much support, such as shifting desert sands, use sidewinding.  The snake pushes and lifts alternate parts of the body in a wave from head to tail while thrusting sideways.  The American sidewinder is one of a few species of desert snakes around the world that use sidewinding as their primary type of movement.

Snakes are as afraid of humans as many humans are afraid of snakes and will use whatever method of movement that works to get away from us; sometimes going between our feet if we’re too close!

Last Updated: 9/18/13