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In actinopterygians, the pelvic fin consists of two endochondrally-derived bony girdles attached to bony radials. Dermal fin rays (lepidotrichia) are positioned distally from the radials. There are three pairs of muscles each on the dorsal and ventral side of the pelvic fin girdle that abduct and adduct the fin from the body. [citation needed]
Anal/cloacal fin The anal/cloacal fin is located on the ventral surface behind the anus/cloaca. The bones that support the anal fin are called pterygiophores. There are up to two series, a proximal series (axonosts) and a distal series (baseosts) Most fish use their anal fin to stabilize while swimming
It has three dorsal and two anal fins. Types of caudal fin: heterocercal (A), protocercal (B), homocercal (C), and diphycercal (D) Sharks possess a heterocercal caudal fin. The dorsal portion is usually larger than the ventral portion. The high performance [definition needed] bigeye tuna is equipped with a homocercal caudal fin, finlets and keels.
Ostraciiform, with almost no oscillation except of the tail fin. More specialized fish include movement by pectoral fins with a mainly stiff body, opposed sculling with dorsal and anal fins, as in the sunfish; and movement by propagating a wave along the long fins with a motionless body, as in the knifefish or featherbacks.
Most male fish have two testes of similar size. In the case of sharks, the testes on the right side is usually larger [citation needed].The primitive jawless fish have only a single testis, located in the midline of the body, although even this forms from the fusion of paired structures in the embryo.
The pelvic fins are extremely reduced and are not used in locomotion. The dorsal fin is absent. The pectoral fins of the African brown knifefish are lengthy and designed to give the animal precise control as it swims. They are often employed in a windmilling motion, in conjunction with the caudal/anal fin, as the fish retreats into its lair.
The dorsal, anal and caudal fins are fused and pelvic fins are lacking. Dorsal fin begins mid body creating a long continuous fin where in other species it begins more posterior and is not as prominent in length. Their body movement depends highly on undulation originating near the anterior axial end.
The body is covered by large, circular scales, the ones on the cheeks and the top of the head and a single scale just above the pectoral fin being the largest. The male is generally larger and more deep-bodied than the female, with larger dorsal, pelvic and anal fins. [4] The color of the sheepshead minnow is olive green above and yellowish below.