Argyropelecus

Argyropelecus is an oceanic ray-finned fish genus in the deep sea hatchetfish family Sternoptychidae. A collective name is "silver hatchetfishes", but this can also refer to a species of the freshwater hatchetfishes which are not particularly closely related to this. The large pupils of these marine hatchetfishes enable them to see dim objects in the deep sea, where light barely penetrates.

Silver hatchetfishes Temporal range: Chattian to Present 27.82–0 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Argyropelecus lychnus, conventional and X-ray images
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Stomiiformes
Family:	Sternoptychidae
Subfamily:	Sternoptychinae
Genus:	Argyropelecus Cocco, 1829
Diversity
7 species

Species

There are currently seven recognized extant species in this genus:^[1]

• Argyropelecus aculeatus Valenciennes, 1850 (lovely hatchetfish, Atlantic silver hatchetfish)
• Argyropelecus affinis Garman, 1899 (Pacific hatchetfish)
• Argyropelecus gigas Norman, 1930 (giant hatchetfish, greater silver hatchetfish)
• Argyropelecus hemigymnus Cocco, 1829 (half-naked hatchetfish, short silver hatchetfish, spurred hatchetfish)
• Argyropelecus lychnus Garman, 1899 (tropical hatchetfish)
• Argyropelecus olfersii (G. Cuvier, 1829)
• Argyropelecus sladeni Regan, 1908 (Sladen's hatchetfish, silvery hatchetfish)

A. prisca, a fossil species from the Oligocene of Romania

The earliest unequivocal fossils of Argyropelecus date from the start of the Chattian stage of the Late Oligocene^[2] The original assessment of Eocene-aged otoliths from Austria assigned to this genus is now questioned.^[2]