Rectilinear Locomotion: Snakes
They have a pair of ribs and a ventral scale to match vertebrae. They have movable ribs, so they can walk in a slow/quiet motion. Unlike worms, snakes only need to lift their ribs to cause the other segments to tilt forward, like millipedes.
Sidewinding Snakes
(Photo courtesy of Shutterstock) They move backward through a ‘stamping-like’ motion. They lift their head and drop it backward to the side. A ‘domino-like action’ will push any remaining segments backward. It is lifting and gravity helps.
Swimming Snakes
It is the same as lateral undulation, but on water. They need lateral lifting. They are not able to swim straight b/o their lighter base. It is all about balance. It is totally different from the undulation of eels.
Lateral undulation: Snakes
The lifting of bending sides causes ground traction via ventral scales. The higher side lifting induces faster speed and less ground contact. They can’t run straight b/o their lighter base.