The hammerhead shark is an easily identifiable type of shark because of its oddly shaped head, but most people do not know that there are actually ten identified species or types of hammerhead sharks.
These are the: winghead shark, scalloped bonnethead, whitefin hammerhead, scalloped hammerhead, scooped, great hammerhead, bonnethead, smalleye hammerhead, smooth hammerhead, and Carolina hammerhead. There is a possible eleventh species discovered recently in 2017! These types of sharks belong to the Sphyrnidae family, which translates from Greek to mean “hammer.”
Out of the 10 known species, only 3 of them are considered aggressive. Hammerhead shark attacks on humans are rare, so hammerheads are not considered to be dangerous to people. However, they should be treated with caution because they are defensive sharks and can attack!
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Habitat
The hammerhead shark can be found in all oceans of the world in both deep and shallow water.
Size/Color
Size depends on the species, but the largest hammerhead sharks can reach up to 20 feet in length and weigh up to 1,000 pounds.
Hammerhead sharks vary in color on their dorsal, or upper, side from gray-brownish to green, but most are off-white on their ventral, or under, side.
Anatomy
As you might have predicted, the hammerhead shark is named for its uniquely shaped head, called a cephalofoil, which is in the shape of a flattened hammer. The shape of the hammerhead shark’s head does more than making it stand out in a crowd. Scientists say the shape of the head allows the shark to search out prey on the ocean’s bottom, especially the shark’s favorite snack ~ sting rays! The shark uses its head to locate its next meal like a human would use a metal detector to find buried treasure.
Differences in the cephalofoil shape are the best way to distinguish between each species of a hammerhead shark. In fact, many of the names of hammerhead sharks include their unique shapes. For example, the scalloped hammerhead has distinct scalloped ridges on its head.
Diet
The hammerhead shark is a predator to fear if you are a sea creature. They are carnivores and eat crabs, lobsters, squid, and other types of fish. Their favorite meal is a sting ray. Hammerheads use their heads not only to detect prey but also as a weapon to capture it.
They often use their heads to trap sting rays on the bottom of the ocean floor. When feasting on a sting ray, the hammerhead eats the spiny tail and all!
Special Adaptations
Hammerhead sharks not only have a special head allowing them to discover sting rays hidden on the ocean floor, but their eyes also are special. Their eyes are widely set apart on their uniquely shaped head, allowing them to scan for prey quickly.
Because of their eye placement, hammerhead sharks’ visual field is thought to be nearly 360 degrees (a complete circle) due to their ability to see above and below their bodies. The only place they cannot see is right in front of their head!
Reproduction
Hammerhead sharks are viviparously giving birth to live babies called pups. The female hammerheads give birth to litters from 6 to 50 pups at one time after carrying the babies for about 11 months. The hammerhead pup’s head is more rounded and much softer than the parent’s and grows into its distinct head shape as it matures.
Conservation Status
All the species of hammerheads are considered to be experiencing a population decline due to overfishing. Two of the species, the great hammerhead and scalloped hammered, are listed as endangered. Seven of the remaining eight species are listed as Near Threatened, Vulnerable, or are yet to be assessed.
There is one species, the bonnethead, listed as Least Concern, but scientists have recently discovered what is thought to be a new species similar to an existing bonnethead that may change this status in the near future.
Fact Attack
- Hammerhead sharks may be the answer to human skin disease. How you may ask, is this possible? Hammerhead sharks are a rare marine, or ocean, an animal that can get a suntan! They like to lie in the sun but never get sunburned!
- Hammerhead sharks live in groups called schools but hunt alone at night. Each school usually has about 10-20 hammerheads, but there have been documented sightings of about 200 individuals in one school!
Resources
http://www.softschools.com/facts/animals/hammerhead_shark_facts/327/
http://kids.nationalgeographic.com/animals/hammerhead-shark/#hammerhead-shark-swimming.jpg
http://www.nationalgeographic.com/animals/fish/group/hammerhead-sharks/
https://www.floridamuseum.ufl.edu/fish/discover/species-profiles/sphyrna-mokarran/
