The basking shark is large in size, with a huge mouth and large gill slits. The shark has a cigar-shaped body and a conical shape of the head and muzzle. The muzzle is very short. Newborns have a distinctive curved muzzle, which acquires “adult” contours during the 1st year of life. The body is covered with a layer of mucus.
Gill slits very long and wide enough. They begin almost at the top of the head and end at the throat. Each slit carries up to 1300 elongated horny gill hairs, forming a peculiar bristle on the anterior edge of the gill slit (so-called, tamped apparatus). Eyes small, round. Mouth large, can reach one meter in width in an open form.
First dorsal fin large, vertical, triangular in shape. Second dorsal fin much smaller than first. Pectoral fins large, up to 2 meters in length. The tail part has the shape of a crescent, the caudal fin itself has a greatly enlarged upper and underdeveloped lower part. The liver of the basking shark is up to 25% of the total weight and contains squalene. The placoid scales have inclined teeth from the head to the tail, because of which, if you hold your hand in the direction of the teeth, the shark’s skin seems smooth, and if held in the opposite direction, it will seem rough.
Teeth of both jaws shallow (not more than 5 mm in height) with one sharp conical apex. In the center of the mouth, teeth have an even vertical vertex, and closer to the corners of the mouth – slightly curved into the mouth. On each jaw about 100 teeth, located in 4-7 rows.
Characteristic body color from deep blue to brown. The back is usually almost black, and the belly is light. Sometimes there are spots of a lighter, slightly contrasting color.The average body length of the basking female shark is 8.9 m, the male one is 6.5 m. The largest specimen of this species was 12.27 m long and the smallest 1.5 m. Newborn sharks, presumably, have length from 1.5 to 1.8 m.