Common Name: no common name for the collective order
Families: 5 - Anoplogastridae (“fangtooths”), Diretmidae (“spinyfins”), Anomalopidae (“lanterneyes” or “flashlight fishes”), Monocentridae (“pinecone fishes”), and Trachichthyidae (“slimeheads” or “roughies”)
Anatomy: deep, stocky body; skin and scale texture varies between families; upturned mouths; some species have bioluminescent bacteria contained in pockets of skin or in light organs near the eyes
Diet: zooplankton; smaller fish, crustaceans, and cephalopods
Habitat: marine pelagic habitats worldwide, from 10 m (33 ft) to as deep as 5,000 m (16,000 ft) down; some species of lanterneye fish migrate to shallow waters near coral reefs at night
Evolved in: Late Cretaceous
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Propaganda under the cut:
While scary in close-up photography, the Common Fangtooth (Anoplogaster cornuta) (image 4) only grows to a total length of 18 cm (7 in). It feeds on smaller fish, crustaceans, and cephalopods.
Most deep sea fish do not have swim bladders, but the Common Fangtooth does.
Fangtooths are most commonly found between 200 and 2,000 m (660 and 6,560 ft) deep, but can be found as deep as 5,000 m (16,000 ft) down, making them one of the deepest-living fish.
Lanterneyes, also known as Flashlight Fishes (family Anomalopidae) (image 1 and gif), have bioluminescent organs located underneath their eyes. These light organs contain luminous bacteria and can be "shut off" by the fish using either a dark lid or by being drawn into a pouch. The light organs are used to communicate, attract prey, and evade predators.
Pinecone Fish (family Monocentridae) (image 2) also have bioluminescent organs filled with symbiotic bacteria, located on either side of their lower jaw. The color of their light varies with ambient light levels: orange by day and blue-green at night. The photophores are thought to play a role in attracting zooplankton, and they may also use them to communicate.
The Orange Roughy (Hoplostethus atlanticus) (image 3) is one of the only Trachichthyiformes to be regularly consumed by humans. But if not caught, they can live for up to 149 years, and are slow to reach maturity. Many populations of Orange Roughy have already crashed, while others are showing signs of severe overfishing. Due to slimeheads' slow rate of reproduction, the sustainability of these fisheries is questionable.
