Christopher Kenaley of Harvard University wanted to understand what benefit (if any) do the needle-shaped teeth endow to this fish family.

What he did was to model the fish’s jaws and teeth using a computer program. He then threw different fish-catching scenarios at the model to see if there was some sort of evolutionary benefit to the jaw and teeth design combination.

A scenario where the fish was laying on its side in the dragonfish’s mouth caused the jaw closure to take upwards of one second — much too long. In this scenario the fish would easily get away.

What if the fish were upright in the mouth instead?  In this case, jaw closure speed increased to 125 milliseconds — a 4x speed increase!  What his results suggest is that maybe the needle-like teeth encourage the prey to stay upright in the dragonfish’s mouth which in turn allows the dragonfish to close its mouth faster.

Check out the below video produced by the Monterey Bay Aquarium Research Institute for video of the fish in this large-toothed family. In order of appearance in the video: Aristostomias scintillans (Shiny loosejaw), Anoplogaster cornuta (Fangtooth), Tactostoma macropus (Longfin dragonfish), Chaenophryne, Chauliodus macouni (Viperfish), Tactostoma macropus (Longfin dragonfish), Chauliodus macouni (Viperfish), Tactostoma macropus (Longfin dragonfish).

(via New Scientist)