Nile crocodile or Common crocodile

Large Crocodile -The male crocodile usually measure from 11.5 to 16 feet long (3.5 to 5 meters), but very old, mature ones can grow to 18 ft (5.5 m) or more - Herodotus claimed that Nile crocodiles have a symbiotic relationship with certain birds like the Egyptian plover, which enter the crocodile's mouth and pick leeches that have been feeding on the crocodile's blood (thanks Wiki for that)