A bull shark can swim up a river from the sea, and bull sharks have a semi-permanent population in Lake Nicaragua. People in different places call the bull shark by different names. In Africa it is often called the Zambezi River shark, or just Zambi. In India it is often called the Ganges shark, and in Nicaragua it is called the Nicaragua shark. The name bull shark comes from its stocky shape and broad, flat snout.

A bull shark can swim up a river from the sea. It can do this because it can adjust the salt and water balance in its body. It copes with fresh water by lowering the urea in its tissues. In fresh water, its kidneys work hard to keep salt in its body. Bull sharks can also live in water as salty as 53 parts per thousand, which is saltier than ordinary sea water.

Female bull sharks are bigger than male bull sharks. Female bull sharks can reach about 4 metres long, while male bull sharks usually grow to about 3.6 metres. According to one aquarium, an average female is about 2.4 metres long and weighs 130 kilograms, and an average male is about 2.3 metres long and weighs 95 kilograms. As of November 2026, the most a bull shark is reported to weigh is 316.5 kilograms (about 698 pounds), and the longest one reported was 400 centimetres (about 13 feet) long.

A museum lists the size at maturity of bull sharks as 157 to 226 centimetres for males and 180 to 230 centimetres for females. The adults are light to dark gray on their backs, and the snout is very short. Bull sharks have small eyes compared with most other sharks in their family.

Bull sharks are opportunistic hunters that eat many different kinds of prey, such as fish, rays, crabs and squid. A bull shark usually hunts alone. It often swims slowly near the bottom until prey appears.

Bull sharks spend most of their time in shallow water. In a satellite-tag study, they spent most of their time in water shallower than 20 metres. They are usually found in water less than 30 metres (about 100 feet) deep, in bays, estuaries, rivers and lakes near the coast.

Over short distances, bull sharks have been recorded swimming at about 19 kilometres an hour (about 11 miles an hour). A bull shark's upper teeth are triangles with jagged edges. In a study that calculated bite force, the largest bull sharks had a calculated bite force of up to 5,914 newtons at the back of the jaws. A newton is a unit of force. The number comes from a calculation, so it shows what the jaws could do, not a bite that anyone measured.

A bull shark pup grows inside its mother, fed through a yolk-sac placenta. The mother carries her pups for 10 to 11 months. She has between 1 and 13 pups at a time.

A newborn pup is about 55 to 80 centimetres long. Bull shark pups are well developed and can swim, and even hunt, soon after birth. Young bull sharks often grow up in river mouths and bays, where the water is not very salty.

Bull sharks have been found hundreds of kilometres from the sea. They have been reported more than 2,000 miles up the Amazon River, in Peru, and as far up the Mississippi River as Illinois. Bull sharks, especially young ones, can travel far up rivers. They live in warm coastal water around the world.

Words to know

• urea: a body chemical
• maturity: being grown up
• opportunistic: eats what's there