What are the four methods of snake locomotion?

The four methods of snake locomotion are serpentine, sidewinding, concertina, and rectilinear movement. Serpentine locomotion involves lateral undulations of the body, allowing the snake to push off surfaces. Sidewinding is used primarily by desert-dwelling snakes to traverse loose sand, moving sideways in a looping motion. Concertina movement involves the snake forming loops and contracting to pull itself forward, while rectilinear movement involves the snake moving in a straight line by stretching and contracting its body segments.