Hammerhead sharks belong to the family Sphyrnidae. There are 9 species of hammerhead shark and 8 of them belong to the genus Sphyrna, which is the greek word for hammer.
The winghead shark is in its own genus called Eusphyra, which is from the greek words eu which means good and sphyrna for hammer. This shark has a very large hammer. You can see a picture of it on Wikipedia: Winghead shark
These are the 9 species of hammerhead shark:
- Winghead shark (Eusphyra blochii)
- Scalloped bonnethead (Sphyrna corona)
- Carolina hammerhead (Sphyrna gilberti)
- Scalloped hammerhead (Sphyrna lewini)
- Scoophead (Sphyrna media)
- Great hammerhead (Sphyrna mokarran)
- Bonnethead (Sphyrna tiburo)
- Smalleye hammerhead (Sphyrna tudes)
- Smooth hammerhead (Sphyrna zygaena)
Depending on the species, hammerhead sharks can be 3 to 20 feet in length and weigh 6.6 to 1,278 pounds. The great hammerhead is the largest species.
Hammerhead sharks can be found in warmer waters worldwide. During the summer, they migrate to cooler waters. Some species can be found in groups called schools during the day and hunt alone at night.
Scientists call the hammer shape of their head a cephalofoil.
It is believed one of the reasons their heads evolved into a hammer shape is to give them better vision. Their eyes are located on the sides of their wide heads and gives them 360 degrees of vision. The wider area also gives them more space for their ampullae of Lorenzini, which are sensory organs called electroreceptors that detect electric fields in water and help them detect their prey.
Hammerhead sharks eat fish, other sharks, squid, octopus, crustaceans, and stingrays. They even use their head as a weapon and to pin down stingrays while they eat them on the bottom of the ocean. Hammerheads have a smaller mouth than other sharks.
Unprovoked attacks by hammerhead sharks are rare, and there have been no known human fatalities.
Most hammerhead species are listed as either vulnerable or endangered due to being hunted for their fins and over fishing.
I really like this video: Friendly Hammerhead Shark by Jonathan Bird’s Blue World