In the deep waters of the Meridian Trench lives a fish known as the duskfin, first documented by researchers in 2003. Unlike most deep-sea predators, the duskfin does not chase its prey. Instead, it relies on a pale organ above its eye that glows faintly blue, flickering in a slow, irregular rhythm that small crustaceans mistake for their own kind.

When a crustacean drifts close enough to investigate the light, the duskfin remains completely still for several seconds, a behaviour researchers call the waiting phase. Only once the prey is within a single body length does the duskfin strike, using a sudden burst of water expelled through gill slits to propel itself forward.

The duskfin's glowing organ is not always lit. During the day, when faint sunlight still filters down from far above, the fish keeps the organ dark, since crustaceans can detect the glow more easily against a brighter background. The light only appears once true darkness sets in, roughly four hundred metres below the surface.

Researchers have also found that young duskfins are born without the ability to control the organ's rhythm, flashing it constantly until around eight weeks old. This early, uncontrolled flashing rarely attracts prey, so juvenile duskfins feed mostly on debris drifting down from higher waters until they mature enough to hunt properly.