''Astronesthes niger'', commonly known as snaggletooth, is a species of small,

deep sea fish Deep-sea fish are fish that live in the darkness below the sunlit surface waters, that is below the epipelagic or photic zone of the sea. The lanternfish is, by far, the most common deep-sea fish. Other deep sea fishes include the flashlight f ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Stomiidae Stomiidae is a family of deep-sea ray-finned fish, including the barbeled dragonfishes. They are quite small, usually around 15 cm, up to 26 cm. These fish are apex predators and have enormous jaws filled with fang-like teeth. They are ...

. It occurs in the tropical and subtropical Atlantic Ocean, the Caribbean Sea and the Gulf of Mexico, as well as the Indian Ocean and western Pacific Ocean, at depths to .

Description

''Astronesthes niger'' is a slender, somewhat elongate, black fish with a large mouth, fang-like teeth, and a long

barbel Barbel may refer to: *Barbel (anatomy), a whisker-like organ near the mouth found in some fish (notably catfish, loaches and cyprinids) and turtles *Barbel (fish), a common name for certain species of fish **''Barbus barbus'', a species of cyprinid ...

on its chin tipped by a knob. This fish grows to a maximum length of about and can be distinguished from other closely related species by its snout lacking a turned up tip, by the barbel being less than 1.7 times the length of the head, and by the swollen portion on the barbel being one third to one half its length. The dorsal fin has 15 to 17 soft rays and is set slightly behind the pelvic fins. There is a ventral adipose fin in front of the anus, and the anal fin has 12 to 15 soft rays. There are two longitudinal rows of

photophore A photophore is a glandular organ that appears as luminous spots on various marine animals, including fish and cephalopods. The organ can be simple, or as complex as the human eye; equipped with lenses, shutters, color filters and reflectors, h ...

s on either flank and there are luminous patches in front of the eye, above the

nostril A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called t ...

s, above the eye, and a large patch above the pectoral fin.

Distribution and habitat

The species is found in the

mesopelagic zone The mesopelagic zone (Greek μέσον, middle), also known as the middle pelagic or twilight zone, is the part of the pelagic zone that lies between the photic epipelagic and the aphotic bathypelagic zones. It is defined by light, and begins a ...

of the tropical and subtropical Atlantic Ocean, the Caribbean Sea and the Gulf of Mexico, between about 40°N and the equator. It is also present in the western Pacific and the Indian Oceans. Although its depth range extends to about , at night it is most abundant at less than about .

Ecology

''Astronesthes niger'' is a predator and feeds on

krill Krill are small crustaceans of the order Euphausiacea, and are found in all the world's oceans. The name "krill" comes from the Norwegian word ', meaning "small fry of fish", which is also often attributed to species of fish. Krill are consid ...

amphipods Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far descri ...

and

lanternfish Lanternfishes (or myctophids, from the Greek μυκτήρ ''myktḗr'', "nose" and ''ophis'', "serpent") are small mesopelagic fish of the large family Myctophidae. One of two families in the order Myctophiformes, the Myctophidae are represented ...

es. It appears to only rise to the very top layer of the

water column A water column is a conceptual column of water from the surface of a sea, river or lake to the bottom sediment.Munson, B.H., Axler, R., Hagley C., Host G., Merrick G., Richards C. (2004).Glossary. ''Water on the Web''. University of Minnesota-D ...

when both the sun and moon are below the horizon, at about the periods of the month when the moon is in its first or third quarter phase; it appears that the fish needs the moon for its vertical migrations but avoids the surface when it is illuminated. Little is known about the reproduction of this fish and the development of its larvae.

References

{{Taxonbar, from=Q2633720 Stomiidae Fish described in 1845