Climate Change May Make The Snapping Shrimp Snap Louder

Tiny snapping shrimp are among of the loudest animals in the ocean. And climate change could be making them louder, which affects a lot of other sea life.

MARY LOUISE KELLY, HOST:

See if you can guess what this sound is.

(SOUNDBITE OF CRACKLING)

KELLY: Bacon frying, maybe a crackling fire? Nope, it is underwater snapping shrimp. They're only a few inches long but among the loudest animals in the ocean. Thanks to climate change, they are getting even louder. That's according to new research. And that could affect a lot of other sea life, as NPR's Lauren Sommer reports.

LAUREN SOMMER, BYLINE: Dive into tropical seas and that crackly sound is hard to miss.

(SOUNDBITE OF SHRIMP CRACKLING)

ARAN MOONEY: Oh, yeah. You can hear them very easily. They tend to live in colonies where they're somewhat clustered closely together, so you hear this chorus of them.

SOMMER: Aran Mooney is a scientist at the Woods Hole Oceanographic Institution who studies some of the many snapping shrimp species around the world. He says that sound comes from their one massive claw.

MOONEY: And they can really close that claw really, really fast, and it makes a bubble in the water. And when that bubble implodes, that's what makes the pop or the snap.

SOMMER: It even creates a tiny flash of light, and it's surprisingly loud.

MOONEY: Really similar to a large ship or a large whale or even some sort of, like, underwater hammering.

SOMMER: During World War II, researchers were sent to investigate the noise because it was interfering with the sonar the Navy used to find submarines. Mooney and his colleagues looked at snapping shrimp in a lab and the wild and found that the warmer it gets, the louder the shrimp are and the more they snap. Warmer water makes them more active, as Mooney recently presented to the American Geophysical Union. And oceans are warming with climate change, says Steve Simpson.

STEVE SIMPSON: When we look at any type of global change, what we realize is that there will be winners and losers.

SOMMER: Simpson is a professor of marine biology at the University of Exeter. He says sound is incredibly important underwater because it's hard to see very far, and oceans are already getting noisier because of human impacts.

SIMPSON: Fifty thousand ships sailing around the world carrying 90% of world trade.

SOMMER: Add louder shrimp to that noise, and it could further stress other animals that use sound, like fish.

(SOUNDBITE OF CRACKLING, GRUNTING)

KELLY: That grunt is a sergeant major, a small Atlantic coral reef fish.

SIMPSON: It could mask the ability of fish to be able to communicate because it will create a higher noise floor, this crackling sound that then swamps any of the sounds that they might be wanting to listen out for.

SOMMER: But there's also a chance that louder shrimp could help other organisms. Simpson says when fish, clams and coral are young larvae, they're free-swimming, floating in the ocean current.

SIMPSON: They're ready to find a reef to go and make their home, and they use the sound that's coming from that community as a cue to find a place to settle.

SOMMER: The sound of snapping shrimp is an advertisement that that reef is a good place to live, which is why Simpson and other scientists will be watching the ocean's soundscape closely at a time when so many things are changing.

Lauren Sommer, NPR News.

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