Fish locomotion is the various types of animal locomotion used by fish, principally by swimming. This is achieved in different groups of fish by a variety of mechanisms of propulsion, most often by wave-like lateral flexions of the fish's body and tail in water, and in various specialised fish by motions of the fins. The major forms of locomotion in fish are: In addition, some fish can variously "walk" (i.e., crawl over land using the pectoral and pelvic fins), burrow in mud, leap out of the water and even glide temporarily through the air.