Common Name
Smooth Lanternshark
Year Described
Lowe, 1839
Identification
This lanternshark is moderately slender with a fairly long snout (longer than mouth width but shorter than the distance from mouth to pectoral origin). Anterior nasal flap is short. There are two dorsal fins, the second being slightly larger than the first. Distance between them is greater than the snout-gill distance. Both have a spine on the anterior margin (averages shorter than bigelowi. First dorsal originates well posterior to pectoral fin tip and almost midway between pectoral origin and pelvic fin origin. Pectoral fin is squared off and small. Anal fin is absent. Pelvic fins originate well anterior to the second dorsal. Caudal fin is fairly long (about distance from snout to second gill slit). Rear margins of fins lack broad fringes. Teeth in lower jaw are broader than the upper jaw. Upper jaw teeth are narrow with a broad, erect central cusp and 2-4 pairs of lateral cusplets. The lower jaw teeth have low and oblique cusps with a lateral notch. Upper jaw: 23-30 teeth; lower jaw: 35-44 teeth. Denticles low without median spine (low, flat crowns and four-pointed bases) and randomly distributed. Skin smooth. Ventral photophores are smaller than skin denticles and scattered amongst them. 10-14 turns in intestinal spiral valve.
Color
Uniform gray to dusky brown body with a pale blotch on the top of the head (pineal spot). There are scattered black markings on the lower head, the lower pectoral fin, the pelvic base, and the caudal base, but are not conspicuous. Fins dark anteriorly with a pale edge. Eye is green in life.
Size
Mature adults from 31-47 cm. Maximum size to ~50 cm.
Habitat
Benthic or oceanic over continental slopes and shelves from 274-1200m (possibly deeper). Feeds on small sharks and various bony fishes.
Range
Reported from the southwest Atlantic (Brazil to Argentina) but confirmed only from the eastern Atlantic. Closest confirmed specimens from the central S. Atlantic.
References
Ebert, D. A., Dando, M., & S. Fowler. 2021. Sharks of the World. Princeton University Press. 607 pp.
Gianeti, M.D. & C.M Vooren. 2008. Identification of the sharks of the genus Etmopterus Rafinesque, 1810 (Elasmobranchii: Etmopteridae) from the upper slope of southern Brazil, with comparison between the species E. bigelowi Shirai & Tachikawa, 1993 and E. pusillus Lowe, 1839. Brazilian Journal of Oceanography, 56, 139-143.
Other Notes
Often confused with Etmopterus bigelowi, which is the only other Etmopterus with smooth denticles. Most of the records from the W. Atlantic appear to be E. bigelowi, but E. pusillus may occur in our area, especially in the Southern Hemisphere. Etmopterus pusillus is separated from E. bigelowi by having less turns in the intestinal valve (10-13 vs. 16-19), a more rearward placed first dorsal fin, and more teeth (22-31/30-53 vs. 19-24/25-39) (Castro, 2011).