11 Incredible Facts About Bull Sharks

These formidable fish are not nearly as simple as they might seem.

bull shark swimming toward camera in empty blue water

Fiona Ayerst / Getty Images

Bull sharks are large, stout predators found in tropical and subtropical waters around the world, typically close to coastlines. Their name is reportedly inspired by their stocky appearance and blunt, rounded snout, as well as their relatively aggressive behavior.

They may lack the widespread name recognition of great whites, but bull sharks are also considered a potential threat to humans who venture into the ocean, with more than 100 historical attacks linked to their species. At the same time, however, a beachgoer is more likely to be killed by rip currents or lightning than by a bull shark (or by any other shark), and these ancient fish face far more danger from us than we do from them.

From their biological quirks to their relationship with our species, here are a few interesting facts you may not know about bull sharks.

Fast Facts

  • Common Name: Bull shark
  • Scientific Name: Carcharhinus leucas
  • Average Lifetime in the Wild: 23 to 28 years
  • Average Lifetime in Captivity: Up to 30 years
  • IUCN Red List Status: Vulnerable
  • Current Population: Unknown

1. Bull Sharks 'Out-Bite' Great Whites

A bull shark bites into a tuna off the coast of Fiji
Terry Moore / Stocktrek Images / Getty Images

Bull sharks mainly eat bony fish and smaller sharks, but they're opportunistic feeders, also taking prey like birds, crustaceans, dolphins, terrestrial mammals, and turtles.

The bite force of bull sharks is among the highest of any fish, according to a 2012 study published in the journal Zoology. The species can bite with a force of 5,914 Newtons, the study found, which is more powerful than the bite of 12 other sharks and sharklike fish the researchers used for comparison—including the great white shark and the great hammerhead.

2. They Can Thrive in Freshwater or Saltwater

bull shark in shallow water
Rainervon Brandis / Getty Images

While most sharks are limited to marine habitats, bull sharks can live for long periods and even reproduce in either freshwater or saltwater. That's because they're capable of osmoregulation, a process in which the sharks can adjust the salt-to-water ratio in their bodies based on the water around them. Thanks to special adaptations from their excretory systems, they retain salt and produce more diluted urine while they're in freshwater, then begin to produce saltier urine again when they're back in the ocean.

3. Age Determines Where They Live

Newborn and juvenile bull sharks prefer freshwater habitats. As the creatures get older, their preferences change, opting for saltwater habitats but continuing to swim into freshwater habitats. In old age, bull sharks stay in saltwater.

4. They Can Swim Surprisingly Far Upriver

A bull shark swims through a river at Costa Rica's Corcovado National Park

pefcon / Getty Images

Bull sharks may generally hang out in the ocean, or at least nearby, but the species has also proven perfectly willing to venture far inland via rivers. In 1937, for example, two fishermen caught a bull shark near Alton, Illinois, some 1,750 miles upriver from New Orleans. The species is also known to travel even farther up the Amazon River, with reports of bull sharks as far upstream as Iquitos, Peru, nearly 2,200 miles from the ocean.

Bull sharks often reproduce in freshwater habitats and can even establish a long-term presence there. Waterways with known bull shark populations include the Brisbane River in Queensland, Australia; the Brahmaputra and Ganges rivers of eastern India; Lake Nicaragua; and Lake Pontchartrain and the Potomac River in the U.S.

5. They Give Birth to Live Young

A pregnant bull shark swims off the coast of Playa del Carmen, Quintana Roo, Mexico.
Ken Kiefer 2 / Getty Images

Bull sharks are viviparous, which means that, unlike most sharks, they give birth to live young rather than laying eggs. Their mating season often occurs in late summer or early fall, and the developing pups are nourished in their mother's body by a yolk-sac placenta. After a roughly 11-month gestation period, the mother gives birth to a litter of one to 13 pups, often opting for a freshwater or low-salinity part of her range, such as coastal lagoons, river mouths, or estuaries.

The parents do not rear their young, but they can help protect them by giving birth in these coastal or inland habitats. While adult bull sharks have no natural predators (aside from humans), their pups can fall victim to other sharks. Since most sharks stick to saltwater habitats, however, the pups may face better odds of survival if they spend some time growing up in a river or lake before venturing out to sea.

6. They Have More Than a Dozen Common Names

Bull sharks are also known by at least 15 other common names in various parts of the world, according to the Florida Museum of Natural History.

These include: requin bouledogue in French-speaking countries; Tiburon sarda in Spain; Zambezi shark or Van Rooyen’s shark in South Africa; the Ganges shark in India (but this name is also given to the freshwater river shark Glyphis gangeticus); the Nicaragua shark in Central America; the freshwater whaler, estuary whaler, and Swan River whaler in Australia; the shovelnose shark, square-nose shark, river shark, slipway grey shark, ground shark, and cub shark in various English-speaking parts of the world.

7. They May Have Been the Inspiration for 'Jaws'

Philadelphia Inquirer front page from July 15, 1916
Library of Congress

The 1974 novel "Jaws," which inspired the 1975 blockbuster film of the same title, was itself at least loosely based on some real-life events. Those include a string of shark attacks off the New Jersey coast in July 1916, in which four people died and one was injured.

The novel and movie both feature a great white shark as the culprit, and that species also has been widely blamed for the 1916 attacks. According to some experts, however, details of the 1916 attacks suggest a bull shark may have been likelier. Great whites are relatively rare in New Jersey, especially in inland waterways, and two of the attacks took place in a creek in Matawan, located about 10 miles from the ocean. Bull sharks are much more commonly found in habitats like this, and although great whites have more of a reputation for attacking people, bull sharks are also considered one of the most dangerous shark species for humans.

8. They Have a Diverse Appetite

Bull sharks feast on bony fish and other bull sharks. Their prey includes stingrays, turtles, seabirds, and dolphins. They are also known to feed on crustaceans and echinoderms like crabs, shrimp, starfish, and sea urchins.

9. Their Digestion Helps Them Distract Predators

Speaking of their appetite, bull sharks have a unique ability to control the rate at which they digest food ... and it comes in handy for their survival! If they're in a situation where there's not enough food in the environment, the sharks digest slower than usual so they require less food. They can also throw up food on demand to distract predators.

10. They Are Much Less Dangerous to Us Than We Are to Them

Bull sharks are often cited as one of the three most frequent attackers of humans. According to the International Shark Attack File (ISAF), they rank No. 3 in terms of overall attacks, with 121 total attacks in the historical record, of which 26 were fatal and unprovoked. That follows only great whites (354 total attacks, 57 fatal and unprovoked) and tiger sharks (138 total, 36 fatal and unprovoked). The ISAF warns all these statistics should be taken with a grain of salt, however, given the difficulty of positively identifying the species behind most attacks.

Despite the statistics, sharks pose a minimal risk to humans overall, and there are easy ways to minimize the risk of being attacked by a shark even further. The odds of an attack are roughly one in 11 million, which pales in comparison to deadlier beach hazards such as boats, rip currents, and lightning. Research suggests sharks do not see humans as enticing prey, and most "attacks" are actually exploratory bites, after which the shark typically moves on. That said, for large predators with powerful bites like bull sharks, even a test bite like this can fatally wound a person, so they should be treated with caution and respect.

While sharks kill fewer than 10 people globally per year, people kill an estimated 100 million sharks every year, largely due to fishing, finning, and accidental bycatch. Along with other hazards like climate change and the decline of prey species, this has raised widespread concern about the future of sharks, keystone predators that play vital ecological and economic roles.

11. They Aren't Protected in Any Part of Their Range

Underbelly of bull shark swimming below fish
Rodrigo Friscione / Getty Images 

Bull sharks are still a common species, found in many warm waters around the world, but even these formidable and flexible predators are at risk from humans. They are listed as vulnerable—elevated in 2021 from a less dire "near threatened" status—by the IUCN, which means they do not currently qualify as endangered even though populations are on the decline.

The IUCN says the bull shark is "caught as target and bycatch in artisanal, industrial, and recreational fisheries across its range with multiple fishing gears including gillnet, longline, and trawl. It is mostly retained for its meat and fins."

They currently lack specific legal protections throughout their range, but there are conservation programs that aim to help populations rebound. In the U.S., the Atlantic Highly Migratory Species Fishery Management Plan, implemented in 1993, enforces restrictions like permit limitations, commercial and recreational quotas, and rules around gear. It additionally raises awareness with shark dealers, holding mandatory shark identification workshops.

In the South, coastal waters in several states become off-limits to gillnets during certain times of year, which helps take the pressure off juvenile bull sharks.

Save the Bull Sharks

  • Don't use gillnets when fishing. These entrap juvenile bull sharks in both freshwater and saltwater estuaries.
  • Choose sustainably sourced seafood by consulting the Monterey Bay Aquarium Seafood Watch guide.
  • Support The Nature Conservancy's bull shark research.
  • Volunteer with organizations working to reduce marine pollution.
View Article Sources
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  2. Habegger, Maria L., et al. "Feeding Biomechanics and Theoretical Calculations of Bite Force in Bull Sharks (Carcharhinus Leucas) During Ontogeny." Zoology, vol. 115, no. 6, 2012, pp. 354-364, doi:10.1016/j.zool.2012.04.007

  3. Heupel, MR, et al. "Shark Nursery Areas: Concepts, Definition, Characterization and Assumptions." Marine Ecology Progress Series, vol. 337, 2007, pp. 287-297, doi:10.3354/meps337287

  4. "Carcharhinus Leucas." Florida Museum.

  5. "The Case of the New Jersey Man-Eater." ReefQuest Centre for Shark Research.

  6. "Species Implicated In Attacks." Florida Museum.

  7. Worm, Boris, et al. "Global Catches, Exploitation Rates, and Rebuilding Options for Sharks." Marine Policy, vol. 40, 2013, pp. 194-204, doi:10.1016/j.marpol.2012.12.034