We've known for a while that sharks can navigate long distances in relatively direct paths (the Great White is even known to traverse the Atlantic Ocean!), but how exactly they do it has been something of a mystery.
Now, thanks to a new study out of the University of California, San Diego, scientists have confirmed that sharks essentially smell their way through the open ocean.
After capturing 26 leopard sharks near La Jolla, California, researchers temporarily impaired the sense of smell for 11 of them. The entire group, which is typically a nearshore species, was then taken about five and a half miles offshore and released.
In order to prevent clever sharks from retracing their steps, the scientists did their best to confuse them, including by masking geomagnetic cues and driving the boat in figure-eight maneuvers.
Researchers found that after four hours, the sharks with a normal sense of smell made their way about 62 percent closer to the shore, "following relatively straight paths." But the sharks with an impaired sense of smell only ended up about 37 percent closer, "following significantly more tortuous paths," according to a press release.
The results suggest that the sense of smell -- likely the ability to pick up on chemical gradients in the water -- contributes greatly to a shark's navigational abilities.
Sharks are built to have a keen sense of smell. Their nostrils, which are used solely for smelling, are lined with specialized cells that pick up on dissolved chemicals in the water, and their brains have enlarged olfactory bulbs, allowing them to detect extremely small amounts of certain chemicals.
This skill comes is especially handy when it comes to hunting prey.
According to the American Museum of Natural History, some sharks can "detect their prey at one part per 10 billion; that's one drop in an Olympic-sized swimming pool!"
Turns out, there's just no throwing them off the scent.
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