Pilot fish follow sharks because other animals which might eat them will not come near a shark. In return, sharks do not eat pilot fish because pilot fish eat their parasites. This is called a "mutualist" relationship. Small pilot fish are often seen swimming into the mouth of a shark to eat small pieces of food from the shark's teeth. Sailors even said that sharks and pilot fish act like close friends. When a ship captured "their" shark, the pilot fish followed the ship. Some people reported that the pilot fish would follow the ship for up to six weeks. And they do show signs of distress in the absence of their shark.