Dragonfish may be only several centimetres long, but with their oversized jaws and rows of fang-like teeth, they can trap and swallow sizeable prey. How these small terrors manage to open their mouths so wide has puzzled scientists, until now. In most fish, the skull is fused to the backbone, limiting their gape. But a barbelled dragonfish can open its jaw up to 120 degrees thanks to a soft tissue joint that connects the fish’s head and spine.
Studies of specimens of barbelled dragonfish, show a flexible rod called a notochord, covered by special connective tissue that bridged their vertebrae and skulls. When the mouths are opened, the connective tissues stretched out. The joint provides just enough room for dragonfish to swallow whole crustaceans and lanternfish almost as long as they are.