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The tail of a shark consists of the caudal peduncle and the caudal fin, which provide the main source of thrust for the shark. Most sharks have heterocercal caudal fins, meaning that the backbone extends into the (usually longer) upper lobe. The shape of the caudal fin reflects the shark's lifestyle, and can be broadly divided into five categories:
The adipose fin is a soft, fleshy fin found on the back behind the dorsal fin and just forward of the caudal fin. It is absent in many fish families, but found in nine of the 31 euteleostean orders ( Percopsiformes , Myctophiformes , Aulopiformes , Stomiiformes , Salmoniformes , Osmeriformes , Characiformes , Siluriformes and Argentiniformes ...
The taxonomic history of the Family Stethacanthidae has been rather complicated because the findings of complete skeletons are very unusual, and as result early workers such as St. John & Worthen, [3] and Newberry [4] were unable to recognise the association of the spine, dentition teeth, and dermal denticles of these sharks.
A second, shorter pair of keels are present below the main keels. The caudal fin is large and crescent-shaped, with the lower lobe almost as long as the upper; both dorsal and ventral depressions (precaudal pits) are at the caudal fin base, and a deep ventral notch is near the tip of the upper caudal fin lobe. [7]
The caudal fin has a strong lateral keel and a crescent shape. Other common names include bone shark, elephant shark, sailfish, and sunfish. In Orkney, it is called hoe-mother (contracted homer), meaning "the mother of the piked dogfish". [5] The basking shark is a cosmopolitan migratory species found in
Caudal/Tail fins: Also called the tail fins, caudal fins are attached to the end of the caudal peduncle and used for propulsion. The caudal peduncle is the narrow part of the fish's body. The hypural joint is the joint between the caudal fin and the last of the vertebrae. The hypural is often fan-shaped.
The anal fin of the male is 2% shorter than that of the female, which may be related to the function of the unusually long claspers. The caudal peduncle is almost cylindrical, and leads to a low caudal fin with a small lower lobe and a ventral notch near the tip of the upper lobe.
The dorsal fins are small, with the first dorsal fin origin lying behind the pelvic fin origins. There is no anal fin. The caudal peduncle is robust and lacks notches at the caudal fin origins. The asymmetrical caudal fin has an indistinct lower lobe and an upper lobe without a notch in the trailing margin. [9]