Deep Sea Hatchetfish

Their scales are silvery, delicate and easily abraded. In some species, such as the highlight hatchetfish (Sternoptyx pseudobscura), large sections of the body at the base of the anal fin and/or caudal fin are transparent. They have perpendicular spines and blade-like pterygiophores in front of the dorsal fin. The anal fin has 11-19 rays and in some species is divided in two parts; almost all have an adipose fin. Their large, sometimes tube-shaped eyes can collect the faintest of light and focus well on objects both close and far. They are directed somewhat upwards, most conspicuously in the genus Argyropelecus. This allows to discern the silhouettes of prey moving overhead against the slightly brighter upper waters