As the ocean’s apex predator, sharks are known for their hunting prowess, whether it’s the Greenland shark’s stealth ambush or the thresher shark’s whip-like tail. Still, there’s a lot experts don’t know about the animals in action, such as their maximum speed and bite power.
Most scientific knowledge of bite force comes from experiments using captive sharks or from computer modeling. Not surprisingly, working with “live, large, charismatic sharks in the wild has major logistical constraints,” says Dan Huber, a biologist at the University of Tampa who studies sharks.
But underwater photographer Brocq Maxey, who helps run the South Africa-based dive company Shark Explorers, wanted to take on that challenge. In an experiment, Maxey managed to record the bite force of a wild, free-swimming tiger shark and a great hammerhead shark—two of the world’s largest predatory sharks—in what is believed to be a first for those species.
Studying bite force helps scientists understand how sharks have evolved their hunting strategies over the past 400 million years to become such efficient predators, says Huber, who wasn’t involved in the new experiment.
It’s also vital data for conservation efforts: The more scientists know about sharks and their behaviors, the more they can develop plans to save them, he says.
And given that the International Union for Conservation of Nature lists the tiger shark as near threatened and great hammerheads as critically endangered, understanding what these declining species eat is vital, Huber explains. If a species has evolved to specialize in a specific prey, such as endangered sea turtles, there will be serious repercussions if that food is no longer available. (Read how oceanic sharks are in major decline.)
Dustbins of the sea
For the experiment, Maxey commissioned a custom-made gauge to measure shark bite force. He designed it to be sensitive enough to get accurate readings, but robust enough to withstand the powerful jaws. Then, in the Bahamas, he used bait to encourage sharks to bite the gauge.
Maxey and his team obtained a 505-pound reading from an 11-foot-long hammerhead, and an 864-pound reading from a nine-foot-long tiger shark. Despite being two feet smaller than the hammerhead, the tiger shark had a bite power that was 70 percent higher. (Read about the most fascinating shark discoveries of the past 10 years.)
Huber says that’s what he would expect based on his mathematical models.
Tiger sharks—sometimes called the dustbins of the sea—are not only more aggressive but also renowned for eating almost anything, including sea turtles. Wrapping their large mouths around the prey, they shake their heads to saw through the turtles’ tough shell. Hammerheads require much less power, grabbing their meal—including stingrays and squid—with one quick bite.
While sharks can have enormous bite forces, this is often “by virtue of their gigantic size,” says Huber. When body size is taken into consideration, their bite power is relatively low compared pound for pound with other animals, such as the hippo (1,827 pounds) and the saltwater crocodile—whose 3,748-pound bite is the strongest in the animal kingdom.
Because they have a “mouth full of steak knives,” he says, large sharks don’t need a strong relative bite to get their food.
How fast can a mako go?
Makos—sometimes called the cheetahs of the deep—are “shaped like torpedoes,” says Marianne Porter, a biologist who studies shark biomechanics at Florida Atlantic University. They’re “sleek and streamlined” right down to their “perfect little point” of a nose, which is ideal for piercing through the water, she says. They’re also propelled by their powerful, crescent-shaped tail.
Though there are some anecdotal reports of makos swimming at 43 miles per hour, Casagrande hoped to be the first to definitively record their top speed.
In a novel experiment off San Diego, Casagrande got a mako shark to chase a fish-shaped lure, then followed the shark with a super-fast, GPS-outfitted drone. The shark took two seconds to swim 72 feet (0.01 mile) as measured by a floating ruler, which was a speed of 24.54 miles per hour. The experiment validated Casagrande’s method, but the speed is very unlikely to be a mako’s fastest. (Read how shark scales give sharks their speed.)
While disappointed, Casagrande understands why no one has yet recorded the definitive top speed of a mako. “It's almost impossible. Almost,” he says in the episode.
Challenges of shark research
Both Huber and Porter caution that it’s hard to determine the top speed or bite force of any animal.
For instance, voluntary bite forces from wild sharks are likely to be “dramatic underestimates,” Huber says, since offering them bait “isn’t a realistic predatory scenario.”
“Yes, the sharks will bite, but there’s no reason why they need to exert themselves to their highest level of performance.”
We humans can relate, he says. “Think about how often you do anything in your life as hard and as forcefully as you possibly can.”
As with bite force, a shark’s speed can vary hugely depending on the situation at the time, says Porter, who wasn’t involved in the speed experiment. “We don’t know if the shark was following this lure out of curiosity, or if it was legitimately trying to capture food like its life depended on it.”
Confirming an animal’s maximum speed would require “huge amounts of data” over a long period of time, she adds, but Casagrande’s small-scale experiment could inspire further experiments.
In particular, she says, using drone video could give scientists unprecedented insight into how sharks can move so incredibly fast.