They occasionally identify new species. But sometimes they find that two sharks that had been considered different species are actually the same. This section describes some of the best-known sharks. They eat only small water organisms called plankton. These sharks have a habit of slowly swimming on the surface.
Bull sharks can live in fresh water.
They often enter rivers that empty into the sea. For example, bull sharks have been captured in the Amazon River in Brazil, in the Ganges River in India, and in the Mississippi River in the United States. They are also found in Lake Jamor in Indonesia and in Lake Nicaragua in Nicaragua. Bull sharks often feed on other sharks and have attacked swimmers. Hammerhead sharks, which include a number of similar species, rank among the strangest-looking sharks.