Hammerhead sharks are known for their distinctive hammer-shaped heads. Instead of the pointed snout of a typical shark, hammerheads have flattened heads with projections on either side that give it the appearance of a hammer (or in some species a shovel) when viewed from above. Their eyes are at the end of these projections. The entire structure is called a “cephalofoil”.
Aside from the head, the body plan of most hammerhead species is similar to the typical shark body plan. Their dorsal fins are large in comparison to most other shark species, and their mouths are relatively small.
Coloration is usually gray, sometimes with a yellowish or greenish tint, and can vary by species. The smallest species of hammerhead are the bonnethead and scalloped bonnethead, which grow to around three to four feet long. The largest species is the great hammerhead, which can grow up to 20feet long.
Aside from their different sizes, the easiest way to tell different hammerhead species apart is the shape of their head. Bonnetheads are also called shovelheads, and are named for the rounded shape of their cephalofoils. The great hammerhead has a T-shaped head, while the scalloped hammerhead has a series of notches in their cephalofoil. The winghead shark is named for it sextraordinarily large cephalofoil, which may be as wide as half of the total length of the entire shark.