Nurse sharks are particularly unassuming sharks, often seen lying motionless on the seabed, or under rocky overhangs. But when it comes to finding a mate, they really start to liven up.

Many sharks also make their homes in the waters near big cities. Scientists found that bull, nurse and hammerhead sharks split time between Miami's noisy, polluted coast and more natural environments.

Sand tiger sharks, also known as gray nurse sharks, have a deceivingly ferocious look. They are large-bodied and display a mouthful of sharp teeth that protrude in all directions, even when the ...