It’s never really been a question of whether sharks can hear well. They can. But measuring how well is difficult.
If hearing is somewhat subjective for us humans, imagine how hard it would be to objectively judge a shark’s hearing. But we recently learned more about a particular breed’s sharp hearing: according to a study published in Integrative Organismal Biology, blacktip sharks off the Florida coast have surprisingly sensitive hearing and can instantly pinpoint where a noise is coming from.
Scientists at Florida Atlantic University parked a boat off southeast Florida. They cranked low-frequency sounds through an underwater speaker and tracked the local shark population using aerial drones. The idea was to startle the sharks with noise they’re not used to and see how they react.
Scientists Played Sounds for Sharks. They Reacted From 243 Feet Away.
And so they did. The blacktips reacted to low-frequency noise up to 74 meters away, or 243 feet. When they heard it, they made sharp, quick turns away from the sound, assuming it was an oncoming threat they’d rather flee than confront. More than 70 percent of the reactions
There is a zone called the “acoustic far field” where sound waves have stretched themselves thin. Researchers previously assumed sharks were basically deaf to sounds in this field, yet 70 percent of black tip sharks’ reactions occurred within the acoustic far field.
This is a little surprising because sharks lack a gas-filled swim bladder, the organ bony fish use to translate sound pressure into vibrations, much like a human eardrum. Marine biologists think black tips rely on a specialized inner-ear structure called a macula neglecta to detect tiny particle movements in distant water.
While it’s fascinating that sharks can hear much better than we give them credit for, it’s probably not reassuring to anyone who already has an innate fear of taking a dip in the ocean because of them. You are probably already pretty terrified of them, and now you know that they can hear you from about three-quarters of an American football field away.
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