Bull Shark

Fascinating facts about the Bull Shark

• A bull shark's kidney filters out salt so efficiently it can drink seawater and live in freshwater rivers — the only shark that swaps between oceans and rivers without dying. They've been caught 4,000 km up the Amazon and in the Mississippi River near New Orleans. Most sharks are locked into salt water; bull sharks rewrote the rules.
• Bull sharks have the highest testosterone levels of any animal ever measured — nearly 7 times higher than a male lion. Scientists think this drives their aggression and their reckless feeding style, where they bite first and investigate later. It's a chemical explanation for why they rank among the most dangerous sharks to humans.
• A pregnant bull shark can carry up to 13 pups at once, and she teaches them to hunt in nursery grounds — shallow bays where pups learn to feed on small fish before venturing into open water. This parental investment is rare in sharks. It's why bull sharks mature slower than many ocean sharks but survive longer.
• Their bite force pounds at 1,275 newtons — three times stronger than a great white's relative to body size — packed into a head that's built like a battering ram. That flat, rounded snout is used to ram prey and flip them over before attacking. It's a design optimised for chaos in murky water where sight doesn't work.
• Bull sharks were nearly hunted to the edge: their fins are valuable in the trade and their meat is sold as fish and chips across Asia and the Caribbean. Populations in the Gulf of Mexico have dropped 75% since the 1970s. They're resilient scavengers, but that resilience has made them targets — and now their survival depends on fishing limits we've only recently started enforcing.

At a glance

About the Bull Shark

In the murky, sun-dappled waters of the world's tropical and subtropical regions, the bull shark reigns as a formidable and enigmatic presence, its stout, broad snout and powerful tail propelling it with deliberate, almost languid ease through the dense vegetation of river deltas and coastal shallows. As it moves, its gray, stocky form seems to blend seamlessly with the surrounding environment, rendering it all but invisible to the unsuspecting prey that inhabit these complex, shifting landscapes. With its remarkable ability to thrive in both fresh and saltwater, the bull shark is a testament to the incredible adaptability of life on Earth.

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