Why Do Bonnethead Sharks Have Bonnet Heads?

The bonnethead, Sphyrna tiburo, also called shovelhead, is a smaller version of the hammerhead shark. Its odd-shaped head contains a multitude of electroreceptors to detect minute electromagnetic disturbances.

Like its hammerhead cousin, the bonnethead feeds by swimming across the sea floor, moving its head in an arc pattern like a metal detector.

Bonnetheads feed primarily on crustaceans, consisting mostly of blue crabs, but also eat shrimp, mollusks and small fishes. To expand its food choices, the shark has small, sharp teeth in front for grabbing soft prey, and flat, broad molars in back for crushing hard-shelled animals.

When its electroreceptors detect a meal hidden in the sand, the shark turns sharply and bites into the sediment. If it’s a crab, the shark uses its teeth to grind the shell, then uses suction to swallow the crab whole.

On average, bonnetheads are about 3 and a-half feet long. They range from New England, where they are rare, to the Gulf of Mexico and Brazil, and from southern California to Ecuador. In spring, summer and fall, they are found off Florida and in the Gulf of Mexico.

Bonnetheads are not considered dangerous to humans. They usually swim in small groups of five to 15 individuals, though schools of hundreds or even thousands have been reported.

PHOTO:  The shovel-shaped head of the bonnethead shark is clear in this underside photo. In summer, bonnetheads are common in inshore waters of the Carolinas and Georgia. Photo by Julie Powers

Information provided by the North Carolina Aquarium at Pine Knoll Shores. The state operates three public aquariums; one in Pine Knoll Shores, another at Fort Fisher and a third on Roanoke Island. The aquariums are administered by the North Carolina Department of Environment and Natural Resources, and are designed to inspire appreciation and conservation of North Carolina’s aquatic environment. For more information about the Aquariums, log onto www.ncaquariums.com, or call 800-832-FISH.

The North Carolina Aquariums wants the public to not just become visually familar with their species on display but to also become knowledgable ambassadors on their behalf.