Dragonfish rule the ocean deeps by virtue of huge, dagger-like teeth rendered nearly invisible by a coating of stealth-inducing nanocrystals.
If you've never been up close & personal with a dragonfish, consider yourself both very lucky and very buoyant. These nightmarish creatures live hundreds to thousands of feet below sea level; so deep that less than one percent of the ambient sunlight can reach them.
This isn't a bad thing for the dragonfish, mind you, since they really don't WANT to be seen... at least, not by their prey. Problem is, dragonfish have gaping mouths studded with fiendishly pointed needle-like teeth. Other sea creatures who catch a glimpse of those choppers make waves in the opposite direction. What's a poor hungry dragonfish to do?
Evolve transparent teeth, of course... hey, we didn't say it was easy! The cool thing about evolution, however, is that given enough time, a successful solution to a problem will take hold. Nobody knows how many generations of dragonfish were born, lived and died before transparent teeth became the norm within the species but here we are... and here they are, making out like bandits in the ocean deep!
Oh, and when we say that dragonfish teeth are “transparent”, we don't mean their formidable fangs are simply clear as glass. Nope, there's more to it than that. Dragonfish, you see, are mildly bioluminescent – their skin emits a faint glow, a fairly common phenomenon in the darkest depths of the world's oceans. That's cool if you're looking for a dragonfish date, not so much if you're frightening off potential prey. Dragonfish teeth, however, don't reflect ANY light regardless of its source.
Scientists from UCSD Jacobs School of Engineering accepted the challenge posed by these “invisible teeth” and published the results of their research in the journal Matter. It would appear the one weird trick employed by dragonfish is right out of Star Trek – Voyager, and we're looking at you, Seven of Nine.
When researchers (including Audrey Velasco-Hogan, above) turned the magnifying powers of an electron microscope on teeth from a dragonfish of the genus Aristostomias, they noticed an interlinked array of grain-size nanocrystals coating the fangs' enamel. The nanocrystals effectively prevented light emitted by the dragonfish from reflecting off its teeth. Pretty nifty... and they do it without resorting to tachyon beams or reversing the polarity of the ship's deflector dish.