View data on Catalog of Fishes here.
Vertebrae (33–35)+(14–16) =48–50, Maximum body depth 5.8–6.7 times in SL. Caudal peduncle depth 2.0–2.5 times in its length, Head length 4.1–4.5 times in SL. Eye diameter 3.8–5.0 times in head length, Chin barbel in small specimens of SL 31–51 mm comparable to head length 0.8–1.2 times in head length, decreasing with growth and, at SL of 58–89 mm, 1.1–1.5 times in head length; at SL of 95–148 mm, 1.5–2.3 times in head length. Terminal bulb of barbel elongated, occupying 115–113 of barbel length. Comblike row of teeth on maxilla has 12–26 slanted teeth, five to eight teeth present on palatine, 15–16 gill teeth present on fist gill arch.
Dorsal-fin rays 15–17, anal-fin rays 13–15, pectoral-fin rays 8. Length of dorsal fin base 2.2–2.5 times greater than that of anal fin. Origin of anal fin is below the first to second terminal rays of dorsal fin or slightly posterior to its end. Pelvic-fin bases anterior to vertical at beginning of dorsal fin. Dorsal adipose fin originates above 9th–11th anal fin ray; ventral adipose fin below 13–14th photophore of VAV series.
Photophores: BR 17–20; IP 9, PV 13–15, VAV 1921, AC 10–12, IC 52–56; OV 12–15, VAL 19–22, OA 34–36. Spaces between photophores four to five times greater than diameter. Second photophore PV series above third photophore of that series. In AC series, one to two median photophores slightly elevated in relation to others. One or two luminous spots present on upper jaw: first spot, found in front of vertical at beginning of orbit, relatively large, round, and dense (it first appears at SL of 26–31 mm). Second luminous spot, if present, elongated and found under anterior part of eye. It is also smaller, not dense, and composed of separate luminous scales. Posterior to operculum, at level of middle of eye, large longitudinally oriented spot of compact luminous issue, stretching further posteriorly to end of anterior of pectoral–pelvic space; in large specimens of SL over 80 mm, length of this spot is 0.9–1.3 of eye diameter (this luminous spot develops after 50 mm SL).
Single (rarely two) luminous spot present on upper jaw, Posterior to operculum, at eye level, large compact luminous spot present; no other spots found over body, Second and third PV photophores at single vertical. Vertebra 48–50; photophores AC 52–56, OA 34–36. Chin barbel with terminal bulb, its length 4.1–9.2 (at SL < 50 mm, 3.5–4.7) in SL. Body depth 5.8–6.7 in SL. Body black.
A. niger, which is found only in the north Atlantic, has a transitional distribution, coinciding with secondary water masses of the North Atlantic.
Parin NV, Borodulina OD. 2002. Preliminary review of Astronesthes niger species group (Astronesthidae, Stomiiformes) with description of six new species from the Atlantic and Indian Oceans. Voprosy Ikhtiologii 42(4):437–458.
Astronesthes niger is a member of the A. niger species group. The following description, based on Parin and Borodulina’s (2002) revision, applies to all species in the group.
Maximum body depth 4.9–6.7 times in SL. Caudal peduncle depth 1.9–2.6 times in its length. Vertebrae (31–35)+(14–16)= 46–50. Head length 3.3–5.0 times in SL. Eye diameter 3.3–5.5 times in head length. Chin barbel small (0.7–3.5 times in head length), its length decreasing with growth. Terminal bulb usually well developed in juveniles (its shape often species specific), but disappearing in majority of species with growth. Premaxilla with five fangs in main row and two to three small lateral teeth. Comb-like row of teeth on maxilla bearing 11–33 teeth, number increasing with growth. One tooth present on anterior head of each vomer. A row of five to eight teeth on palatines. Gill teeth 14–17 on first gill arch.
Dorsal-fin rays 14–17, A (rarely 12) 13–15, pectoral-fin rays 7–9 (usually eight). Pelvic fin bases situated just in front of vertical at beginning of dorsal fin, sometimes slightly more posteriorly. Beginning of anal fin at level of three posteriormost rays of dorsal fin or posterior to end of its base. Dorsal fin base length 1.7–2.5 times greater than that of anal fin. Dorsal adipose fin originates above 9th to 12th anal–fin ray; ventral adipose fin below 12th to15th photophore of VAV series.
Photophores: BR 17–19(rarely 20), IP 9, PV 12–15, VAV 17–21, AC 10–12, IC 50–55(rarely 56); OV 11–14(rarely 15), VAL 19–22, OA 31–35(rarely 36). Serial photophores of average size, with interphotophore spaces four to six times greater than photophore diameter in adults. Ventral row forming steep curve below base of pectoral fin; three posteriormost photophores of IP series increasingly elevated and three anteriormost photophores of PV series usually steeply descending to level of remaining photophores of ventral row. In AC series. first photophore often elevated compared to others, middle one or two photophores also elevated. Numerous additional photophores present on head and body. In small specimens (SL 30–60 mm), these photophores occur along ventral body margin in regular rows that gradually disappear with growth.
Spots of luminous tissue present on head and body. On upper part of head of small specimens (SL 30–50 mm), spots conspicuous between nostrils, above both orbits, and on nape region. Spots becoming more sparse in adults, transforming into aggregations of separate small "scales" of luminous tissue. There are one to three luminous spots on the skin covering the premaxilla in front of anterior margin of orbit and below anterior part of orbit.
Skin under or covering anterior margin of anterior spot (single or largest one) strongly pigmented; second and third spot, if present, significantly smaller with a more simple morphology. In anterodorsal part of operculum, small spot of luminous tissue present, which is also well distinct in small specimens, but transforming in adults into aggregation of dispersed luminous scales. Luminous spot present on body (large or small), situated posterior to operculum and appearing at a standard length of 40–70 mm. Aggregation of luminous tissue can be found above lateral photophore row below dorsal fin, between lateral and ventral rows below bases of pectoral fin, in front of pelvic fin base.
Postorbital light organ below middle part of orbit or further posteriorly and separated from orbit by dark pigment fold; organ sexually dimorphic, as in other species of the genus. In females, this light organ is small and rounded; in males, significantly larger and oval. Photogenic gland very small, found in middle of light organ in females and in posterior part in males.
Body black, fading to brown or beige in preservative. Fin membranes lightly colored, rays slightly pigmented. Chin barbel (including terminal bulb) with pigment only on anterior part of base; thin and pigmented stem visible inside barbel.
Parin NV, Borodulina OD. 2002. Preliminary review of Astronesthes niger species group (Astronesthidae, Stomiiformes) with description of six new species from the Atlantic and Indian Oceans. Voprosy Ikhtiologii 42(4):437–458.
To 160 mm SL.
Locality unknown (supposed to be China seas).
Holotype: BMNH 1970.5.19.1.
Astronesthes niger, commonly known as snaggletooth, is a species of small, deep sea fish in the family Stomiidae. 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 1,000 m (3,300 ft).
Astronesthes niger is a slender, somewhat elongate, black fish with a large mouth, fang-like teeth, and a long barbel on its chin tipped by a knob. This fish grows to a maximum length of about 16 cm (6.3 in) 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 photophores on either flank and there are luminous patches in front of the eye, above the nostrils, above the eye, and a large patch above the pectoral fin.[2]
The species is found in the mesopelagic zone of the tropical and subtropical Atlantic Ocean, the Caribbean Sea and the Gulf of Mexico, between about 40°N and the equator.[2] It is also present in the western Pacific and the Indian Oceans.[3] Although its depth range extends to about 1,000 m (3,300 ft), at night it is most abundant at less than about 100 m (300 ft).[2]
Astronesthes niger is a predator and feeds on krill, amphipods and lanternfishes.[2] It appears to only rise to the very top layer of the water column 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.[4] Little is known about the reproduction of this fish and the development of its larvae.[3]
Astronesthes niger, commonly known as snaggletooth, is a species of small, deep sea fish in the family Stomiidae. 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 1,000 m (3,300 ft).
