Although most of the 500+ species of shark are totally harmless to humans, cantankerous bull sharks can be a different story, says Melissa Hobson.
- The weirdest sharks on the planet, including one that can walk: Discover some of the ocean's strangest creatures
- Incredible shark facts: 34 hard-to-believe facts that celebrate this fascinating, yet much-maligned fish
One of the “Big Three” – alongside great whites and tiger sharks – these predators are considered one of the sharks most likely to bite humans (although negative encounters are still insanely rare).
What are bull sharks?
Big, bold, and bulky, bull sharks (Carcharhinus leucas) are considered one of the world’s most dangerous shark species. These solitary sharks can be highly territorial.
Like bulls, these huge, hulking animals can be crotchety and are known for headbutting. They have several nicknames, including Zambezi shark, river shark and freshwater whaler because of their ability to tolerate brackish and freshwater as well as salt water.
How dangerous are bull sharks to humans?
Bull sharks are considered one of the most dangerous species of shark to humans (although the risk of you having a negative encounter with one are still incredibly low), along with tiger sharks (Galeocerdo cuvier) and great white sharks(Carcharodon carcharias).
According to the Florida Museum of Natural History’s International Shark Attack File, there were 47 unprovoked shark bites on humans in 2024 (from all species). Of these, bull sharks were the main culprit. Although humans aren’t a natural prey item for these large predators, even an accidental or investigative bite can be fatal.
Even so, you’re more likely to die from getting caught in a rip current, being struck by lightning or even taking a selfie than being bitten by a shark (of any species).
What do bull sharks look like?
Bull sharks are recognisable by their sturdy build and blunt, rounded nose, and they are brownish grey in colour with a paler belly. They have small eyes, broad, triangular teeth, five gill slits, a large, triangular front dorsal fin and a small rear dorsal fin
How big are bull sharks?
These immense predators can reach around 3.5 metres, with females growing slightly larger than males. They weigh between 90–230 kg
What do bull sharks eat?
Although bull sharks can be aggressive towards humans, we are not part of their natural diet. These carnivores feed in both marine and freshwater ecosystems and have a varied diet. In the ocean, they eat fish, sharks, rays and whale carcasses as well as birds, turtles, invertebrates and marine mammals, like dolphins. They also hunt freshwater fish
How do bull sharks hunt?
These predators often hunt in turbid water with bad visibility so their prey can’t see them coming. They have a very good sense of smell, which leads them to their target in the murky water.
Once bull sharks identify their prey, they use an iconic hunting strategy known as the ‘bump and bite’. Before going in for the kill, they headbutt the animal. This might be a way of finding out more about it or to disorient it before coming back with a deadly bite.
Where do bull sharks live?
As well as their aggressive nature, one reason some people are so afraid of bull sharks is because they can live very close to human settlements. These large sharks like tropical and warm waters globally and are often found in shallow coastal waters.
Unlike most species of sharks, bull sharks can tolerate brackish and even freshwater for long periods of time thanks to their specially adapted kidneys and liver. This means they can also be found in estuaries, lagoons, lakes and rivers – which is why they’re sometimes referred to as river sharks. Females usually give birth in freshwater and the young can spend several years in these protected habitats before venturing our to sea.
Bull sharks can travel thousands of miles away from the ocean. This species has been found 1,700 miles inland in the Mississippi River and 2,400 miles away from the sea in the Amazon River (one of the deadliest rivers in the world).
In Brisbane, Australia, there was even a population of six bull sharks living in a stagnant lake on a golf course between 1996 and 2013. They had become trapped there as juveniles after severe flooding and lived there for 17 years.
How long do bull sharks live?
Their average lifespan is around 25 years
How do bull sharks reproduce?
Bull sharks reach sexual maturity at around 10 years old. After mating, the embryo develops inside the mother’s body (unlike some species such as small spotted catsharks and horn sharks, which lay eggs) for between 10 months and a year.
When she’s ready to give birth, the female usually swims to freshwater, like a river mouth. She delivers up to 13 live babies in one litter and they come out tail-first.
Already measuring nearly a metre long, these pups are fully self-sufficient as soon as they’re born. They can swim and fend for themselves and it’s not long before they can hunt too so they don’t need any care from their mother.
Are they under threat?
Bull sharks are categorised as vulnerable by the IUCN Red List for Threatened Species. Like other marine animals, populations are being negatively impacted by warming waters, pollution and overfishing. Bull sharks are targeted by fishers for their meat and fins and can also be caught as bycatch.
Because they swim in brackish and freshwater – like rivers and estuaries – as well as coastal waters close to shore, bull sharks are also affected by habitat loss when humans develop the coastline, build new homes or hotels, expand agricultural efforts, or dam rivers.
In countries like Australia and South Africa, they can also be killed by shark nets – these nets are put into the water near popular beaches to catch large sharks, often killing them or other marine species. The idea is that shark nets reduce the risk for swimmers but many people argue that, as well as harming marine life, the nets don’t work as a bite prevention method because sharks can swim around them.
