Medical News
Life
5 June 2019
Dragonfish live in the deep sea and have transparent teethAudrey Velasco
By Ruby Prosser ScullyDeep-sea fish have evolved transparent teeth which, along with their black bodies, make them invisible to prey.
While dragonfish are only the size of a pencil, they are fearsome predators at the top of the food chain. Their thin, eel-like bodies support a huge black mouth filled with razor-sharp teeth, that can widen to swallow prey half their size.
Marc Meyers at the University of California San Diego and his colleagues have discovered what makes these teeth almost entirely transparent.
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Using an electron microscope, they found that the teeth contain grain-sized nanocrystals spread throughout the enamel. Materials are transparent when light can pass through them with little scattering, and because these structures in the surface of the teeth are so small, they don’t scatter or reflect much light.
Dragonfish teeth are made from an outer enamel-like layer and an inner layer made of dentin. They are sharper than piranha teeth and probably as hard as a great white shark’s teeth, says Meyers. Having thinner teeth than many other predatory fish also helps reduce their visibility, he says.
Their dark-skinned bodies already help dragonfish camouflage into the inky blackness of the deep ocean, and they use a light-emitting lure near their mouths to entice prey toward them.
But the evolution of transparent teeth means that this bioluminescence doesn’t reflect onto their teeth and blow their cover. This means the mouth would be invisible to prey right until the moment it was caught.
“I would see a mysterious light source toward which I would be attracted,” Meyers says describing the prey’s final moments. “Suddenly, I would be trapped and pierced.”
Journal reference: Matter, DOI: 10.1016/j.matt.2019.05.010
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