Sperm whales are so loud that their clicks are capable of killing a human within their vicinity, says one science and adventure journalist.

James Nestor, an avid ocean-goer and author, claimed in a recent presentation that a fellow diver was swimming alongside a pod of sperm whales when one approached him out of curiosity. He put his hand up to protect himself and his hand ended up paralyzed for nearly 4 hours.

“These clicks are so powerful in the water that they can blow out your eardrums easily, and they can actually vibrate a human body to death,” he said.

Sperm whales are the loudest mammals on the planet, with vocalizations reaching an astonishing 230 decibels. For reference, a jet engine from 100 feet away produces about 140 decibels. At around 150 decibels your eardrums will burst, and the threshold for death is estimated to be in the range of 180 to 200.

And, sound travels differently underwater than it does through air, which means those 200+ decibel clicks are far more amplified than they would be on land. Science writer Maggie Koerth-Baker at FiveThirtyEight explains:

“Because water is denser than air, sound in water is measured on a different decibel scale. In air, the sperm whale would still be extremely loud, but significantly less so — 174 decibels, [which] is loud enough to rupture people’s ear drums. Suffice to say, you probably don’t want to spend a lot of time swimming with the sperm whales.”

Despite their abilities, sperm whales are unlikely to use lethal force on us humans. They mainly use sound to communicate, investigate their surroundings, and navigate the big blue.

How do they generate such powerful sound?

The colossal toothed whales pass air through nasal passages which is subsequently forced through two lips called “monkey lips” at the front of its nose just below the blowhole. (The production of sound is similar to air passing through the neck of a balloon.) The sound is then amplified by a fatty, wax-filled organ called the spermaceti organ that sits on top of the skull. The clicks then bounce off a portion of the skull and are directed back outward through the spermaceti organ.

It’s estimated that sperm whales can hear one another hundreds, perhaps even thousands of miles away using this technique.

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