Few wonders of the sunless depths appear quite so ghoulish or improbable as anglerfish, creatures that dangle bioluminescent lures in front of needlelike teeth. They are fish that fish.

Typically, the rod of flesh extending from the forehead glows at the tip. Anglerfish can wiggle the lure to better mimic living bait. Most species can open their mouths wide enough to devour prey whole, using their fangs not only as daggers but as bars of a cage. Some can open their jaws and stomachs so wide as to trap victims much larger than themselves.

(Note: this portrayal applies only to female anglerfish. The males, with rare exceptions, are puny.)

Anglerfish came to the attention of science in 1833, when a specimen of the bizarre fish — a female — was found on the shores of Greenland. Since then, scientists have learned most of what they know by pulling dead or dying specimens from nets. Lifestyle clues have been sparse.