Each of the fins are used in a different manner. There are one or two fins present along the dorsal midline called the first and second dorsal fin. These are anti-roll stabilizing fins. These two fins may, or may not have spines at their origin. When spines are present they are defensive, and may also have skin glands associated with them that produce an irritating substance.
Pectoral fins originate behind the head and extend outwards.
These fins are used for steering during swimming. Pelvic fins are found near the claoca and are also stabalizers. In males they are modified into copulatory organs called claspers. Anal fins may be absent, but if present they are located between the pelvic and caudal fins. The tail region itself consists of the caudal peduncle and the caudal fin.