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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 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 ).
There are 126 bones in the human appendicular skeleton, includes the skeletal elements within the shoulder and pelvic girdles, upper and lower limbs, and hands and feet. [1] These bones have shared ancestry (are homologous) to those in the forelimbs and hindlimbs of all other tetrapods, which are in turn homologous to the pectoral and pelvic ...
Limbs are attached to the torso via girdles, either the pectoral girdle for the forelimbs, or the pelvic girdle for the hindlimbs.In terrestrial tetrapods, the pectoral girdles are more mobile, floating over the rib cage connected only via the clavicles (to the sternum) and numerous muscles; while the pelvic girdles are typically fused together anteriorly via a fibrocartilaginous joint and ...
The bones to which the pectoral fin is attached. peduncle Usually referred to as the caudal peduncle, the region of the body between the end of the anal fin and the base of the caudal fin. pelagic Living on or in the open seas. pelvic girdle The bones to which the ventral fins are attached. pelvic fins Paired fins behind or below the pectoral fins.
Originally, the pectoral and pelvic girdles, which do not contain any dermal elements, did not connect. In later forms, each pair of fins became ventrally connected in the middle when scapulocoracoid and puboischiadic bars evolved. In rays, the pectoral fins are connected to the head and are very flexible.
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 down through the water, turning sharply, and stopping quickly. In gobies, the pelvic fins are often fused into a single sucker disk that can be used to attach to objects.
Pectoral and pelvic fins have articulations resembling those of tetrapod limbs. These fins evolved into legs of the first tetrapod land vertebrates, amphibians . They also possess two dorsal fins with separate bases, as opposed to the single dorsal fin of actinopterygians (ray-finned fish).