A whale shark, feeding off the coast of Mafia Island in Tanzania. Whale sharks have a mouth that can be up to 1.5 m (4.9 feet) wide, containing 300 to 350 rows of tiny teeth and 10 filter pads which it uses to filter feed. They are one of only three known filter feeding shark species, eating zoo-plankton, small fish and fish eggs. Feeding occurs either by ram filtration, in which the fish opens its mouth and swims forward, pushing water and food into the mouth, or by active suction feeding, in which the animal opens and closes its mouth, sucking in volumes of water that are then expelled through the gills. Then filter pads serve to separate food from water. Although massive in size, whale sharks are docile fish and sometimes allow swimmers to hitch a ride. They are currently listed as a vulnerable species, however they continue to be hunted in parts of Asia, such as the Philippines.