This month we're showcasing the Bull Shark. So named for their short, blunt snout and cantankerous nature...

Generally solitary animals, Bull Sharks like to be left alone and can be very territorial. They’re also known to ram their prey, or potential rivals. Adopting a hunting strategy known as bump-and-bite.

They often hunt in murky waters with low visibility, so rely on their keen sense of smell to find prey. Once located they’ll charge their prey head-on and continue to bump and bite them until they're too exhausted to swim away.

They have a diverse diet, primarily made up of fish (including other sharks and rays). They'll also eat crabs, shrimp, starfish, sea-urchins, turtles, birds and dolphins.

When food is scarce, Bull Sharks can slow down their digestion, enabling them to eat less at a time. To avoid being eaten by predators, they also have a neat little escape plan. They'll regurgitate their food to act as a distraction, while they make a hasty get-away.

Probably one of the most incredible things about Bull Sharks though is their remarkable ability to survive in freshwater. Only around 5% of shark species can, and most of them only for a short time. Yet the Bull Shark may live here for years. They can travel huge distances up rivers and have been found as far as 2,500 miles from the sea up the Amazon River.

The biggest issue marine sharks face when entering freshwater is maintaining the correct balance of water and salt in their body. To prevent massive water intake through osmosis, their body must quickly remove excess salts. Otherwise, they could swell to the point of bursting.

Key to the Bull Shark’s ability to thrive in these two environments are their:

  • Kidneys - these produce large amounts of urine, enabling the rapid removal of salts and excess water. When in freshwater the Bull Shark will urinate over 20 times more than in the sea.

  • Liver – produces urea as required depending on the salinity of the environment.

Yet even Bull Sharks have their limits. A recent study discovered that they can only survive in a freshwater habitat for 4 years. This is likely due to a lack of food. Highlighting how important both marine and freshwater habitats are to the life cycle of a Bull Shark.

Their age determines where they live. Estuaries and freshwater habitats provide relative safety for young pups to develop. Here they’re out of reach from many predators, such as other shark species and larger Bull Sharks. As they get older, Bull Sharks develop more of a tolerance for saltwater and start venturing out to sea.

Reproduction is one of the main reasons Bull Sharks seem to travel into rivers. Females will often give birth here or in estuaries by river mouths. Bull Sharks have been seen leaping up river-rapids, just like salmon do, to reach inland lakes.

They give birth to live young every two years in late spring and summer. Although, in warmer places this may take place year-round. After a gestation period of 10-11 months, pup’s are born fully independent at 56-81cm long. Litter sizes can range from 1-13, but are usually between 6 and 8.

Females reach sexual maturity at 18 years (175-235cm). Males at 14-15 years (157-226cm). And they’re thought to live up to 24 years in the wild.

  • SCIENTIFIC NAME: Carcharhinus leucas

  • FAMILY: Carcharhinidae (Requiem Sharks)

  • MAXIMUM SIZE: 4m

  • DIET: Varied. Includes fish, crabs, shrimp, starfish, sea-urchins, turtles, birds and dolphins.

  • DISTRIBUTION: Worldwide in warm, shallow waters along coasts and in rivers. 

  • HABITAT: Found at 0-150m deep, but usually no deeper than 30m.

  • CONSERVATION STATUS: Near Threatened


Related Links:

► Check out more incredible sharks and rays covered in our Creature Features

► Discover more fin-tastic facts by visiting our Discover Sharks section