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Today on Animal Fact Files were going to be talking about hammerhead sharks. If you like learning facts about animals then subscribe to this channel so you can stay up to date on all the new content.

Perhaps not as well known for its attitude like some other shark species, hammerheads tend to be known for their namesake, i.e. that insanely shaped noggin. There are ten species of hammerhead sharks with Carolina hammerheads being the most recently discovered back in 2013. Bonnethead sharks are included as hammerhead sharks and all ten species belong to the Sphyrnidae family. That iconic hammer shape is referred to as a cephalofoil and there are a couple of reasons why these sharks may have developed this way. With their eyes positioned at the tips of their face, hammerheads are allowed a 360 degree vertical view of their world meaning they can keep a pretty close eye on potential meals. Of course, this does mean that they are a bit lacking in having the ability to see right in front of them. They make up for this with sensory organs called ampullae of Lorenzini which are also found in other cartilaginous fish. The ampullae of Lorenzini are used to detect electric fields in the water. All living organism give off some sort of electric field and hammerhead sharks are able to pick up on that. Plus, with a wider head, it’s possible for them to have more receptors and thus be more sensitive to the movements of their prey. This helps them in finding their favorite food: rays. Although rays tend to spend time hidden beneath the sand, hammerheads are able to detect their electric fields and scoop them from the sea floor. They’ll even use their hammer-shaped head to hold prey down while they eat because their mouths are actually pretty small.

While hammerhead sharks prefer rays, they also eat other fish, squid, octopus and even each other from time to time. There has even been some controversy over whether or not some species of hammerheads eat sea grass. Bonnetheads have been observed consuming seagrass and digesting up to 56% of the organic matter found within. Still, they’re not sure whether or not this is actually helping to sustain these sharks or if it’s just a learning curve of hunting as they tend to find young sharks with more seagrass in their diet than more experienced, older sharks. Larger species of hammerhead, such as the great hammerhead, are more likely to eat smaller sharks than the smaller species. However, smaller hammerhead sharks do something pretty amazing to help combat this.

A behavior rarely observed in any other shark species, hammerheads form schools up to 500 individuals. It’s still not entirely understood why this takes place but something odd to note about this is that they tend to only school during the day. At night the sharks will disperse and go off to hunt on their own. Some suggestions for why this happens are that it is for protection because, as mentioned previously, it tends to be the smaller sharks schooling while larger hammerheads tend to travel alone. It could also be used for protection during the mating season. A lone female may be bombarded by a wondering drove of male hammerheads, but with a group the female has more options to be picky. Safety in numbers!

When hammerheads do mate, everything happens internally. A recently observed behavior in captive bonnetheads also seems to indicate that hammerheads may be the first cartilaginous fish to show parthenogenesis or reproduction without fertilization. This is kind of cool because this actually means that asexual reproduction has been observed in all major jaw vertebrate lineages except mammals (unless you count Jesus). Fertilized by a father or not, the young will develop inside the mother’s body and after about 9 months she’ll give birth to anywhere from 10 to 50 live baby sharks - also called “pups.” They’re on their own after that, however, because Mom and Dad don’t take any part in raising them. Hammerheads have been observed to have an average lifespan of around 25 to 30 years but depending on the species may be able to live even longer.

The size of hammerhead sharks varies pretty drastically between the species. They can grow anywhere from 3 feet (1 meter) all the way up to 20 feet (6 meters). The largest hammerhead sharks, the great hammerheads, can weight up to 1,000 pounds (454 kg) but smaller species may weigh as little as 6 pounds (2.7 kg). They appear grey/blue and sometimes even olive colored along their back while their undersides are a lighter color to help with camouflage against the bright light shining through the surf. They can even get a tan from the sun’s rays as they spend a lot of time near the top of the water column or in more shallow water. They live worldwide in warm, temperate and tropical waters and, although they are pretty widespread, some species of hammerheads are endangered due to hunting. Recently, measures have been taken to try and help reduce the amount of endangered hammerheads killed per year.

In Hawaiian culture, sharks were revered as gods and it was believed that when a person died she would be able to transform into a shark that would help protect and defend her living relatives. These sharks were referred to as the family’s ‘aumakua.’ Even today it’s believed that seeing a hammerhead in the waters of Maui is a sign of balance in the ocean and that families are being watched over.

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