Great Hammerhead Shark Facts
- The longest great hammerhead shark measured at 20 feet, and the heaviest weighed a whopping 1280 pounds!
- Great hammerhead sharks prefer shallow waters and are usually found up to 262 feet deep. However, they have been found at depths of 984 feet.
- Researchers believe great hammerhead sharks are cannibalistic and sometimes eat their own young.
- Great hammerhead sharks love to eat stingrays and have been found with their stingers protruding from their mouths, which means they are immune to their venom.
- The great hammerhead shark’s gestation period lasts for 11 months, and they give birth to between 6-42 pups.
The Story Behind Its Scientific Name
The great hammerhead shark’s scientific name is Sphyrna mokarran, a mixture of Greek and Arabic meaning “great hammer.” A German naturalist explorer Wilhelm Peter Eduard Simon Rüppell first discovered the species in 1837. Because of his two major expeditions to northern Africa in 1817, he helped create the Natural History Society. On his second expedition from 1831 to 1834, near Eritrea on the Red Sea, Wilhelm witnessed a great hammerhead shark stranded on a sandbank while trying to catch its prey. He noticed that it differed from the four species already documented by French zoologist Achille Valenciennes. So Wilhelm crowned it with the Arabic name mokarran, which means “great.”
Behavior
The great hammerhead is a solitary predator but has been known to swim in schools from time to time. They are aggressive hunters and will attack if threatened. Although they do not actively seek out humans, attacks have been recorded.
However, there have only been 16 attacks documented between 1900 and the present, and none of them resulted in death. The majority of these attacks have occurred off the coast of Florida, California, and Australia.
Appearance
Because their eyes sit on the edge of their mallet-shaped heads, they have excellent eyesight and a 360-degree view of their surroundings, making them skilled hunters. They also have a group of sensory organs called the ampullae of Lorenzini, the function of which is to detect electrical fields created by other animals. This aids the great hammerhead in finding its food, especially prey like flounders or stingrays that hide under the sand. See what it looks like swimming in the ocean in the video below:
Habitat
Great Hammerhead Sharks are found worldwide, mostly in shallow waters over continental shelves and island terraces.
However, they also venture out to deeper waters well offshore. They are generally found at depths of 3 feet but can reach depths of 262 feet if needed. Their favorite habitats are usually continental and insular coral reefs with abundant food.
Diet
The great hammerhead shark is no picky eater; they have a broad diet that includes:
- Stingrays
- Small sharks
- Bony fish
- Crustaceans
- Squid
- Octopus
They use their unique sensory function, electroreception, and 360-degree vision to find their prey and pin them down so they can’t swim away.
Predators and Threats
Due to the great hammerhead shark’s immense size, it has few known predators. However, bull sharks prey upon the pups, and the adults are hunted and killed by killer whales. Their biggest threat, though, is the human race because severe overfishing has led to the decline of this unique species. Their large pectoral fins are of great value in the Chinese market, which is why fishermen target them. In addition, their habitat is dwindling, and they are listed as critically endangered on IUCN’s Red List.
Another interesting fact is scientists have documented cannibalism within the species. Some adults will attack, kill, and eat the pups.
Reproduction, Babies, and Lifespan
Their reproduction process is similar to other sharks, where the male uses his clasper to fertilize the female’s eggs through her cloaca.
Great hammerheads reproduce in a Viviparous nature. The mother’s eggs hatch inside of the uterus, and she gives live birth to about 6-42 pups. While in the uterus, the pups receive nutrients through an umbilical cord connected between their pectoral fins, which is attached to a placenta. The female’s gestation period lasts 11 months; once the pups are born, they are left to fend for themselves. While this doesn’t sound very maternal, the females give birth in bays or estuaries where Mangrove forests can shield and protect the pups. If the pups reach adulthood, their average lifespan is between 20 and 30 years.
Population
There is no data that exists on the great hammerhead’s population size. But unfortunately, there is data suggesting that their population is on the decline, which is why they are listed as critically endangered. Great hammerhead sharks in the Indian Ocean, Mediterranean Sea, and Atlantic Ocean have significantly decreased in their populations. Scientists have concluded that their population has reduced by 80% in the last 70 years.