Argyropelecus hemigymnus, a deep sea hatchetfish, has photophores along the lower side of its body. These produce a dim blue light. A predator looking upward from below might see the fish silhouetted by the dim light from the ocean's surface but the counterillumination conceals the fish. This individual was captured in a trawl between 450 and 600 meters depth in the Gulf of Mexico, 2007.