The basking shark is one of the largest known sharks, second only to the whale shark. The length is 6.7-8.8 meters and the weight is about 6000 kg. The largest basking shark specimen was entangled in a herring net in the Bay of Fundy, Canada, in 1851. Its total length reached 12.27 meters and it weighed 19 tons. The basking shark has a cave-like jaw (up to 1 meter wide, which remains open when feeding), long and obvious gill slits (almost surrounding the entire head, and has more complete gill rakers), and smaller eyes. Thin and smaller average waist circumference. The basking sharks teeth are much smaller and hook-shaped, only about 5-6 mm. In basking sharks, only the first 3-4 rows of teeth in the upper jaw and the 6-7 rows of teeth in the lower jaw are functional. The basking sharks caudal peduncle has many keels, its skin is covered with scute scales and a layer of mucus, its snout is pointed and its tail fin is half-moon shaped. Larger basking sharks can flap their dorsal fins. The body of the basking shark comes in many different colors. Generally, the back is dark brown to dark blue or black, and the belly is dark white. Many times they will be found with scars on their bodies, possibly from attacks by lampreys or sharks. The basking sharks liver, which accounts for 25% of the body weight and almost the entire length of the abdominal cavity, is believed to play an important role in controlling their floating and sinking and long-term energy storage. In female basking sharks, only the right ovary is still functional, a characteristic unique among sharks. [1] The basking shark has a spindle-shaped body with a thicker trunk. There is a protrusion on both sides of the tail peduncle, and a depression on the top and bottom of the tail base. The head is large, slightly flattened laterally, and tapered. The muzzle is short and rounded. The eyes are slightly small, round, and have no nictitating membrane. The nostrils are narrow and located in front of the mouth. The anterior nasal valve is short and round; there is no oronasal groove or tentacles. The mouth cleft is wide and arc-shaped, with lip folds; the lower jaw is short, and the teeth are not exposed when the mouth is closed. The jaw teeth are small and numerous, conical in shape, with smooth edges, tooth heads backward, and no lateral tooth heads. 4 to 7 rows are in use, with more than 100 teeth per row on each side. The spray holes are small and round. There are 5 gill openings, which are very wide and extend from the dorsal side to the ventral surface, located behind the eyes. The gill rakers are slender, densely packed, horny, with flat sides at the base and bristle-like ends. They are filtering organs for feeding. There are 2 dorsal fins, the first dorsal fin is large and slightly equilateral triangle, starting between the pectoral fin and the pelvic fin, the rear edge is concave, the upper corner is slightly rounded, and the lower corner is slightly pointed; the second dorsal fin is quite small, starting behind the rear end of the pelvic fin , the rear edge is concave, the upper angle is pointed and rounded, and the lower angle is slightly pointed; the pectoral fin is wide and large, sickle-shaped, the rear edge is slightly concave, the outer angle is obtuse, and the inner angle is obtuse; the caudal fin is forked, the caudal axis is slightly upward, and the upper caudal fork is smaller It grows up, has a notch near the end of the tail, and the lower tail fork is shorter. The dorsal side of the body is grayish brown; the ventral side is white.
