Shark, Hammerhead

The great hammerhead is a very large shark with the characteristic hammer-shaped head from which it gets its common name. The font margin of the head is nearly straight with a shallow notch in the center in adult great hammerheads, distinguishing it from the smooth hammerhead and scalloped hammerhead. The first dorsal fin is very tall with a pointed tip and strongly falcate in shape while the second dorsal is also high with a strongly concave rear margin. The origin of the first dorsal fin is opposite or slightly behind the pectoral fin axil with the free rear tip falling short to above the origin of the pelvic fins. The rear margins of the pelvic fins are concave and falcate in shape, not seen in scalloped hammerhead (S. lewini). The posterior edge of the anal fin is deeply notched.