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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:
Some reports calculate the total length by adding the caudal fin to the pre-caudal length, or by stretching the caudal fin to the maximum possible (sometimes referred to as stretched total length). These methods ignore the angle at which the tail naturally sits, which artificially increases the total length of the shark being measured.
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.
For example, the whale shark reported by Kaikini et al. (1959) was reported at 12.1 m in total length, the precaudal length was reported at 9.84 m, and the upper caudal fin was 2.31 m. Reaching the reported total length of 12.1 m would require the upper caudal fin to be illustrated at a very shallow angle.
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
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 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 pelvic fins are almost as large as the first dorsal fin and bear long, thin claspers in males. The second dorsal and anal fins are tiny, with the former positioned ahead of the latter. Crescent-shaped notches occur on the caudal peduncle at the upper and lower origins of the caudal fin. The upper caudal fin lobe is enormously elongated as ...