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On the other hand, rays rely on their enlarged pectoral fins for propulsion. Similarly enlarged pectoral fins can be found in the extinct †Petalodontiformes (e.g. †Belantsea, †Janassa, †Menaspis), which belong to Holocephali (ratfish and their fossil relatives), or in †Aquilolamna (Selachimorpha) and †Squatinactis (Squatinactiformes).
A peculiar function of pectoral fins, highly developed in some fish, is the creation of the dynamic lifting force that assists some fish such as sharks in maintaining depth and also enables the "flight" for flying fish. Certain rays of the pectoral fins may be adapted into finger-like projections, such as in sea robins and flying gurnards.
Fins allow the sharks to be able to guide and lift themselves. Most sharks have eight fins: a pair of pectoral fins, a pair of pelvic fins, two dorsal fins, an anal fin, and a caudal fin. Pectoral fins are stiff, which enables downward movement, lift, and guidance. The members of the order Hexanchiformes have only a single
The pectoral fins are as long or longer than the head, with a nearly straight front margin and broad tips. The first dorsal fin is large with a rounded apex, and is placed behind the pectoral fins. The second dorsal and anal fins are tiny. The caudal peduncle is expanded laterally into strong keels.
The pectoral fins act as pivots around which the fish can turn rapidly and steer itself. The paired pectoral and pelvic fins control pitching, while the unpaired dorsal and anal fins reduce yawing and rolling. The caudal fin provides raw power for propelling the fish forward. [3]
The pectoral fins of a mobuliform swimming ray experience a spanwise dorsoventral deformation that is highest at the tip and a chord-wise traveling wave. [3] Kinematically mobuliform swimming consists of low frequency, high amplitude fin flapping with less than one waveform present on the fin at a time.
The fish also has much longer lower pectoral-fin rays, the fins on the side of the body. The fins are “extended” and more full compared to other scorpionfish that live in the area, the ...
The pectoral fins are large, but not clearly demarcated from the body, and together with the body are known as the disc. They start from the side of the head in front of the gill openings and end at the caudal peduncle. There are up to two dorsal fins but no anal fin. A slender tail is clearly demarcated from the disc.