Bull Shark Threat: They Swim Where We Swim

Brian Handwerk
for National Geographic News
July 19, 2005

Bull sharks are chewing up the headlines this summer. The predators have been linked to two highly publicized attacks that left one teen dead and another seriously injured in the Florida Panhandle last month.

Though over 375 shark species have been identified by science, just three species are responsible for most attacks on humans: the great white (Carcharodon carcharias), tiger (Galeocerdo cuvier), and bull shark (Carcharhinus leucas).

Bull sharks are the least known of the three. But experts note that the species's preference for coastal waters less than a hundred feet (30 meters) deep makes bulls potentially the most dangerous sharks of all.

"Bull sharks inhabit quite shallow waters, which means that they do have a great opportunity to interact with humans, because the two species tend to share the same areas," said George Burgess, curator of the International Shark Attack File at the Florida Museum of Natural History in Gainesville.

Bull sharks are among the most common sharks in Florida waters and are often encountered by divers.

Shark Attacks

The sharks are especially at home in areas with lots of freshwater inflow, such as brackish river mouths. The abundance of such habitat along the coasts of the northern Gulf of Mexico east of the Mississippi River makes this area especially suited to the sharks.

Bull sharks happily tolerate the murky water found in estuaries and bays. Such conditions can sometimes play a role in spurring shark attacks on humans.

"Visibility is a huge factor in shark attacks," Burgess said. "That's one of the reasons we suggest that people avoid murky water situations when they go into the water."

For the most part, bull sharks dine on bony fishes or smaller sharks—but they sometimes aggressively tackle much larger prey.

"They are one of the few warm-water, coastal sharks that will attack big prey," said Mike Heithaus, a shark expert at Florida International University in Biscayne Bay. "In addition to small fish, they might attack a sea turtle, another shark, or the occasional dolphin."

"They are one of the few sharks that will tangle with prey that's the same size or even bigger than them," the marine biologist added. "Most sharks only go after prey that's substantially smaller than they are."

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