What type of wave do the contractions of the snake muscles make as the snake moves forward

Actually, there are four kinds of reptile motion: 

Concertina - vermiform. Circular muscles around the snake squeeze the front of the snake's body out long, then the latter half is pulled forward. 

Rectilinear crawling - Belly scutes are moved forward individually in a wave-like motion. 

Side-winding - Snake's version of "walking". Use by several species to move over fluidic substrates, such as sand. 

Lateral undulation - Most common form of movement. Snake presses on alternating pressure points to force body forward (or backward)

(taken from a user on Yahoo from Correct Answers)

Nonmetals usually react by gaining electrons

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