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![Hammerhead school.](http://www.scienceiq.com/Images/FactsImages/ACF330.jpg)
Hammerheads can smell a drop of blood in one million drops of water - from a quarter-mile or 400 meters away. The wide space between the nostrils might also help the hammerhead sniff out the direction its prey is moving. The head's shape helps the hammerhead swim and dive, giving lift the same way wings help an airplane fly. Some hammerheads even 'speak' with their heads, and with other parts of their bodies as well. Bonnetheads shake their heads, swim in circles as if chasing their own tails, arch their backs, and raise their heads high. Sometimes they jerk up and down abruptly, or perform a corkscrew, twisting around while swimming fast in a circle.
The
hammers on hammerhead sharks are soft at birth. As the shark grows, its
hammer hardens. Unlike most sharks, hammerheads swim in schools.
Perhaps these are known as the schools of hard knocks?