Dragonfish are armed with dagger-like invisible teeth; scientists now know why

SAN DIEGO, Calif. — Deep-sea dragonfish possess an unusual weapon that they wield extremely well when it comes to luring, capturing and killing their unlucky prey: invisible, dagger-like teeth lining their gaping mouths.

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The dark-colored fish, which can eat prey half the size of its body, feed at the bottom of the sea where sunlight rarely penetrates and their translucent teeth help them surprise their prey. Instead of glowing white in the dark environment, the fish's deadly chompers are nearly impossible to see.

Now scientists know why the bottom feeder's teeth, which are made from the same minerals as shark or human teeth, for example, appear transparent.

Tiny structures inside the teeth reduce the amount of light scattered by the teeth, making them next to impossible to see in the dark depths of the sea, according to a new study published in the journal Matter.

"We suggest that the nanostructured design of the transparent dragonfish teeth enables predatory success as it makes its wide-open mouth armed with saber-like teeth effectively disappear, showing no contrast to the surrounding blackness of the fish nor the background darkness of the deep sea," researchers said in their study summary.

"They look like monsters," Marc Meyers, study co-author and University of California, San Diego, scientist, said, according to Science News. "But they're mini monsters — about as long as a pencil."

Meyers said dragonfish aren't the only animals with transparent teeth but this is the first study to examine how light interacts with the teeth.

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