Surprise: Fish In Acidic Waters Grow Bigger Ears

WASHINGTON – Listen up! Carbon dioxide being absorbed by the oceans is having a puzzling effect on fish — their ears get bigger. Now, that doesn't mean you're going to reel in the Mr. Spock of the sea. Fish ears are inside their bodies. But, as in humans, their ears perform a major role in sensing movement and whether the animal is upright — abilities that are important for survival.

"It was a surprise," biological oceanographer David M. Checkley of the Scripps Institution of Oceanography at the University of California, San Diego, said of the discovery.

"The assumption is that anything that departs significantly from normality is an abnormality, and abnormalities at least have the potential for having deleterious effects," Checkley said.

The ear structure in fish is known as an otolith and is made up of minerals. Checkley and colleagues knew that increasing carbon dioxide in the oceans — absorbed from the atmosphere — is making the sea more acidic, which can dissolve and weaken shells. They wondered if it also would reduce the size of the otoliths.

Just the opposite, it turned out, the researchers report in Friday's edition of the journal Science.

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