Taal Lake is also home to one of the world's rarest sea snakes, Hydrophis semperi. This particular species is only one of two true sea snake (Hydrophiinae) species that are known to live entirely in freshwater (the other is Hydrophis sibauensis from the Sibua River, Borneo, Indonesia ). Bull sharks, Carcharhinus leucas, used to be part of the lake's once-diverse ecosystem but were extirpated by the locals by the 1930s.