page_title: Fish locomotion
section_title: Thunniform
hierarchical_section_title: Fish locomotion / Swimming / Body/caudal fin propulsion / Thunniform
context_page_description: Fish locomotion is the variety of types of animal locomotion used by fish, principally by swimming. This however is achieved in different groups of fish by a variety of mechanisms of propulsion in water, most often by wavelike movements of the fish's body and tail, and in various specialised fish by movements of the fins. The major forms of locomotion in fish are anguilliform, in which a wave passes evenly along a long slender body; sub-carangiform, in which the wave increases quickly in amplitude towards the tail; carangiform, in which the wave is concentrated near the tail, which oscillates rapidly; thunniform, rapid swimming with a large powerful crescent-shaped tail; and ostraciiform, with almost no oscillation except of the tail fin. More specialised fish include movement by pectoral fins with a mainly stiff body, as in the sunfish; and movement by propagating a wave along the long fins with a motionless body in fish with electric organs such as the knifefish.
  In addition, some fish can variously "walk", i.e., move over land, burrow in mud, and glide through the air.
context_section_description: The thunniform group contains high-speed long-distance swimmers, and is characteristic of tunas and is also found in several lamnid sharks. Here, virtually all the sideways movement is in the tail and the region connecting the main body to the tail (the peduncle). The tail itself tends to be large and crescent shaped. This form of swimming enables these fish to chase and catch prey more easily due to the increase in speed of swimming, like in barracudas.
caption: Tunas such as the bluefin swim fast with their large crescent-shaped tails.
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