Bull sharks have strongest bite of all shark species

Bull shark Bull sharks bite hard

Bull sharks have the strongest bite of any shark species, scientists have discovered.

Relative to their body size, bull sharks bite harder than other, larger predatory sharks.

Adult bull sharks can bite with a maximum force equivalent to 6,000N, a study of their jaws and jaw muscles has shown.

It is unclear why bull sharks have such strong bites, which are much greater than required to kill and eat prey.

Details of the discovery are published in the journal Zoology.

Maria Habegger of the University of South Florida in Tampa, US and colleagues in the US and Germany examined bite forces produced by 13 species of shark and their close relatives.

Jaws close up

Great white shark: BBC Nature

The species tested ranged from the 1m-long ratfish, a small relative of the sharks that scours the seabed for crabs and clams, to the great white shark, a large predatory shark that can approach 6m in length. Great white sharks feed on a variety of fish and marine mammals such as seals and dolphins.

Previous research has shown that large predatory sharks have very strong bites.

"We expect strong bite force values in the larger sharks that occupy top positions in the food chain, for example, the great hammerhead, great white shark, tigers and bull sharks," Ms Habegger told BBC Nature.

"These species usually prey upon large prey items such as dolphins, turtles and other sharks, so high bite forces are expected due to the mechanical demands of this type of prey."

But research has also shown that smaller species, such as ratfishes, have high bite forces for their size, perhaps due to their need to crush hard shells.

Start Quote

Bull sharks can bite harder than a great white shark and great hammerhead”

End Quote Maria Habegger, University of South Florida, Tampa

"So sometimes size is misleading. Although larger size sharks will exert higher values of bite force, the relative value of bite force is what matters, pound per pound how strong is the bite?," said Ms Habegger, who is studying for a PhD.

So Ms Habegger, her supervisor Dr Philip Motta, who has long studied the bite forces of sharks, and colleagues estimated the bite forces of the 13 species.

They dissected specimens to study their jaw muscles and worked out the forces these muscles can impart while closing the jaw.

The researchers then used mathematical techniques to remove the effect of body size, so they could make a fair comparison between species.

"What this study shows is that pound per pound bull sharks have the largest bite force value among all studied sharks," said the biologist.

"Bull sharks can bite harder than a great white shark and great hammerhead."

Dr Habegger says the research raises an intriguing question, however. Why do bull sharks need such a powerful bite?

Bullish predator

Bull shark
  • The bull shark (Carcharhinus leucas) is a member of the requiem shark family, which includes the tiger and lemon shark
  • It prefers warm, shallow waters and is known to swim up rivers, often considerable distances, for example 2,220 miles (3,700 km) up the Amazon River in Peru, and over 1,800 miles (3,000 km) up the Mississippi River in Illinois
  • Bull sharks can reach 3.5m long, and are so named for their large, stout heads, and pugnacious nature

The bite forces bull sharks impart change through their lifetime: smaller bull sharks actually bite harder than expected for their size, but larger individuals do not.

One idea is that this ability gives young bull sharks an advantage over other competing species; allowing them to eat more diverse prey earlier in their lives.

But overall, bull sharks, which the research shows can bite with a force of almost 6,000N at the back of the jaw and more than 2,000N at the front, seem to have bites that are too powerful.

"From our knowledge there is no need of such massive values to break fish skin or even to puncture bone," Ms Habegger told BBC Nature.

Strong jaws might be needed to crack turtle shells, as researchers still do not really understand how strong they are.

Or it could be that a strong bite is particularly useful when hunting in murky waters, such as those that bull sharks inhabit.

"In a lower visibility environment catching prey may be more difficult than in open water. So once you get a prey between your jaws, securing it is crucial to not lose your meal."

The possibility remains, though, that the huge bite forces are simply an artefact of the large size these top predators can attain.

Join BBC Nature on Facebook and Twitter: @BBCNature.

More on This Story

Related Stories

The BBC is not responsible for the content of external Internet sites

More from nature

  • Cardinal fish and ostracodFish filmed spitting 'fireworks'

    Film crew captures ostracods' spectacular defensive lightshow that makes predatory fish spit them out.

  • Arapaima'Locally extinct'

    A giant fish which used to dominate the Amazon river is now absent in many areas

  • DragonflyRapid reactions

    Dragonfly's super quick reactions recorded in slow motion by BBC film-makers

  • Wingless adult male of the midge Belgica antarcticaExtreme survivor

    Antarctic midge's small genome may be an adaptation to its extreme environment

  • Myotis midastactus specimen (previously identified as Myotis simus)Golden discovery

    A bat from Bolivia is described as a new species by scientists

  • Dinosaurs 'shrank' to become birds

    Huge meat-eating, land-living dinosaurs evolved into birds by constantly shrinking for over 50 million years, new research shows.

  • Would we starve without bees?

    Honey bees are under threat, and as pollination significantly contributes to the food we eat, what would we do without them?

  • Eggshells may act like 'sunblock'

    Birds' eggs show adaptations in pigment concentration and thickness to allow the right amount of sun for embryos, scientists say.

  • Female shrimps are more aggressive

    Female snapping shrimps are more aggressive than males when defending their territories despite their smaller claw size, a study shows.

BBC iWonder

  • Honey bee close-upInsect intelligence

    Are honey bees as smart as your sat nav?

  • Tyrannosaurus rex skull (c) Mark Williamson / Science Photo LibraryDinosaur dynasty

    One group of dinosaurs survived and their descendants can be seen all around us today

  • Brown rat cluse upRise of the rodent

    Reports of giant, 'super rats' are filling the headlines. But why are we being overrun by rats?

  • Cuckoo portraitHoliday hotspot

    What makes the UK such an attractive destination for visiting wildlife?

Awesome! And there's nothing common about such beauty.

Elaine Bernon on Facebook comments on the trio of common blue butterflies in our Photo of the Day.

Things To Do


More Nature Activities >

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.