How many dorsal fins do most sharks have?

Most sharks have two dorsal fins.

Dorsal fins are the fins along a shark’s back. The first dorsal fin is usually larger and positioned farther forward, while the second dorsal fin is smaller and closer to the tail. Together, they help stabilize the shark and prevent its body from rolling as it swims.

A typical shark also has paired pectoral and pelvic fins, an anal fin and a caudal, or tail, fin. Counting these gives most sharks eight fins in total. The exact shape and position of the fins vary widely between species, reflecting differences in speed, habitat and swimming style.

“Most” matters because sharks are not anatomically identical. Members of the order Hexanchiformes, including the sixgill and sevengill sharks, have only one dorsal fin. Some other shark groups lack an anal fin. These exceptions are why a question about shark anatomy should refer to the usual arrangement rather than every species.