Why do different species of hammerhead sharks have differently-shaped heads?
Eight species of hammerheads are known, each with a differently-shaped head. It is believed that all hammerheads derived from the same ancestor but, as the descendents spread out and inhabited new regions, variations in hammer shape appeared. Some variations offered advantages in certain habitats but not in others. Because different habitats feature different conditions, different hammer shapes proved best adapted (most advantageous) in each region. Today, we have eight distinct species of hammerhead, each with a somewhat different hammer shape.
