The bull shark (Carcharhinus leucas), also known as the "Zambezi shark" (informally "zambi") in Africa, and "Lake Nicaragua shark" in Nicaragua, is a requiem shark commonly found worldwide in warm, shallow waters along coasts and in rivers. It is known for its aggressive nature, and presence in warm, shallow brackish and freshwater systems including estuaries and rivers. Bull sharks can thrive in both salt and fresh water and can travel far up rivers. They have been known to travel up the Mississippi River as far as Alton, Illinois, about 700 miles (1100 km) from the ocean. However, few freshwater human-shark interactions have been recorded. Larger-sized bull sharks are probably responsible for the majority of near-shore shark attacks, including many bites attributed to other species.Unlike the river sharks of the genus Glyphis, bull sharks are not true freshwater sharks, despite their ability to survive in freshwater habitats.