Dragonfish pierce prey with transparent, nanostructured teeth

The deep-sea dragonfish Aristostomias scintillans lurks 500 m beneath the ocean’s surface, where the only visible light comes from bioluminescence. The creatures are only about 15 cm long, but they are voracious predators capable of eating fish up to half their size. These dragonfish lure their prey with glowing photophores along their dark, sleek bodies and with a light-producing barbel that sprouts from their chins. What unsuspecting prey do not see when they approach the dragonfish are the long, spiky teeth protruding from their gaping jaws. That’s because in the deep sea these teeth are transparent, thanks to nanoscale structures that reduce light scattering (Matter 2019, DOI: 10.1016/j.matt.2019.05.010). Researchers led by Marc A. Meyers of the University of California, San Diego, studied the dragonfish’s saber-like teeth and found that they are made of a highly mineralized enamel-like layer consisting of 20 nm crystals of hydroxyapatite in an amorphous matrix of enamel. This layer surrounds the tooth’s dentin, which is made of an array of collagen nanofibrils (5 nm in diameter) embedded in a hydroxyapatite matrix. These nanostructures don’t reflect or scatter light underwater, effectively making the teeth invisible. The researchers hope to make materials inspired by these teeth using nanocrystals and ceramics.