Leeches of the sharks, also known as pilot fishes, Naucrates ductor, are thin gray fish (70 to 90 cm long). On the top of the head those fish have coil in a form of pumps that can be used to attach themselves to any moving object (whales, sharks, turtles). How ever they prefer to live in community with sharks. It’s believed that these little fish chose sharks for protection and free meal of sharks leftovers. Also, by attaching to sharks they get a free ride even if they are pretty swift swimmers themselves. Naturalists think that they do that because they are just lazy.