Concertina movement

Concertina movement is the movement occurring in snakes and other legless organisms that consists of gripping or anchoring with portions of the body while pulling or pushing other sections in the direction of movement. Each point on the snake's body goes through alternating cycles of static contact and movement, with regions propagating posteriorly (i.e. any point on the snake will change from movement to stasis or vice versa shortly after the change occurs in the point anterior to it). This movement is quite strenuous and slow compared to other methods of locomotion. Energetic studies show that it takes more calories per meter to use concertina locomotion than either sidewinding or lateral undulation. In snakes, there are two currently recognized modes of concertina locomotion.