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The pectoral and pelvic fins are paired, whereas the dorsal, anal and caudal fins are unpaired and situated along the midline of the body. For every type of fin, there are a number of fish species in which this particular fin has been lost during evolution (e.g. pelvic fins in † Bobasatrania , caudal fin in ocean sunfish ).
Well developed fins are used for maintaining balance, braking and changing direction. 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 ...
"Cephalic fins": The "horns" of manta rays and their relatives, sometimes called cephalic fins, are actually a modification of the anterior portion of the pectoral fin. Pelvic/Ventral fins: Found in pairs on each side ventrally below the pectoral fins, pelvic fins are homologous to the hindlimbs of tetrapods. They assist the fish in going up or ...
Several synapomorphies support this hypothesis, such as the presence of: sclerotic ossicles, paired pectoral fins, a dermal skeleton with three layers (a basal layer of isopedin, a middle layer of spongy bone, and a superficial layer of dentin), and perichondral bone. [10] Other groups Other groups † Pteraspido-morphi (extinct)
They used paired pectoral and pelvic fins for locomotion. The pectoral fins developed into forelegs (arms in the case of humans) and the pelvic fins developed into hind legs. [50] Much of the genetic machinery that builds a walking limb in a tetrapod is already present in the swimming fin of a fish. [51] [52]
Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hindlimbs of tetrapods, [1] which evolved from lobe-finned fish during the Middle Devonian.
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 latter has lost the paired fins, possibly as a consequence of an adaptation to burrowing habits. [2] The class Osteostraci (meaning "bony shells") is an extinct taxon of bony-armored jawless fish, termed "ostracoderms", that lived in what is now North America, Europe and Russia from the Middle Silurian to Late Devonian.