The smooth hammerhead shark is one of nine species of hammerhead sharks. It is distinguished from other hammerheads by its rounded head (cephalofoil) that’s free of notches seen on other species, such as the scalloped hammerhead shark and the great hammerhead shark. These rounded heads give smooth hammerhead sharks superior depth perception and a 360-degree view of their surroundings.1
The smooth hammerhead shark is one of the larger hammerhead species, reaching average lengths of 8 to 11.5 feet (2.5 to 3.5 m) and a maximum length 16.4 feet (5 m) and weight of 880 pounds (400 kg).1
Smooth hammerhead sharks mate via internal fertilization and give birth to live young. On average, female smooth hammerhead sharks give birth to 33 pups per litter. These pups are raised in nursery habitats of sandy, shallow waters no deeper than 33 feet (10 m). If these pups survive to adulthood, they may live for 20 years or longer.2
The smooth hammerhead shark is a highly mobile species that can be found worldwide in coastal, temperate and tropical waters. Smooth hammerhead sharks typically stay in shallow waters around 65 feet (20 m) deep but have been spotted at depths up to 656 feet (200 m). They are active predators that eat a variety of prey also found in coastal waters, including fish like hake, dolphins, skates and rays, crustaceans, cephalopods (octopus and squid), sea snakes and other sharks. Smooth hammerhead sharks are known to cannibalistically eat smaller members of their own species.1
Like most sharks, smooth hammerhead sharks have special sensory cells in their heads used to detect electric fields produced by other fishes. These electroreceptors allow smooth hammerhead sharks to more accurately locate prey, especially those buried in the sand like stingrays.3 Smooth hammerhead sharks use their hammer-shaped heads to pin down their favored food, stingrays.2
Adult smooth hammerhead sharks have no natural predators, but may very rarely experience predation from opportunistic killer whales that are lacking their normal food sources. Juvenile smooth hammerheads are vulnerable to predation from other shark species, as well as adults of their own species.1
Smooth hammerhead sharks are overfished throughout much of their geographic distribution. Because of their coastal habitats and valuable fins, smooth hammerhead sharks are caught intentionally and as bycatch by a variety of fishing gears, including gillnets, longlines, handlines, bottom trawls and purse-seines. It is estimated that 1.3 to 2.7 million fins are collected each year from smooth and scalloped hammerhead sharks for the shark fin trade.2 Smooth hammerhead sharks are also valued for their liver oil, which is used in vitamins, as well as their meat, which is cooked for human consumption in Floridian and Caribbean markets. Although many populations are overfished beyond the smooth hammerhead shark’s high reproductive capacity, others are not, giving the species a global status of vulnerable to extinction.2
1. The smooth hammerhead shark is named for its smooth, un-notched head that’s unlike other hammerhead shark species.
2. Smooth hammerhead sharks grow to a maximum length of 16.4 feet (5 m) and weight of 880 pounds (400 kg).
3. Smooth hammerhead sharks have one of the highest reproductive rates of open ocean fishes, birthing anywhere from 29 to 53 pups at a time.1
4. Smooth hammerhead sharks are responsible for only 21 recorded unprovoked attacks on humans, resulting in 2 fatalities.
5. Smooth hammerhead sharks do not have a mid-dorsal fin, contributing to the “smoothness” of species.4
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