Bonnethead tend to be larger than males. The Greek word "sphyrna" translates as "hammer", referring to the shape of this shark's head; "tiburo" is the Taino word for shark. Bonnethead sharks are the only sharks known to exhibit sexual dimorphism in the morphology of the head. Adult females have a broadly rounded head, whereas males possess a distinct bulge along the anterior margin of the cephalofoil. This bulge is formed by the elongation of the rostral cartilages of the males at the onset of sexual maturity and corresponds temporally with the elongation of the clasper cartilages. The pectoral fins on most
Scalloped bonnethead mallet-shaped head, called a cephalofoil, is moderately wide (24-29% of total length) and elongated lengthwise. The front margin is broadly arched, with shallow lateral and medial indentations, and no prenarial grooves. The mouth is small and strongly arched. The anal fin is long and has a nearly straight rear margin. Its coloration is gray above and white below, with no prominent fin markings. The similar scoophead ("Sphyrna media") can be distinguished by a shorter snout, a broader mouth, and a deeply concave anal fin margin. Like other hammerheads, the scalloped bonnethead is viviparous, with presumably two pups per litter. The