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The blackmouth lanternshark is a species of dogfish shark within the family Etmopteridae. This species is part of a subgroup that includes one other species from within the family. It is known to inhabit the benthic zones of the Eastern Indian Ocean and the Arafura Sea. These sharks were first described in a 2002 issue of Cybium, and there is still much unknown about the species.

Blackmouth lanternshark
Conservation status
Least Concern  (IUCN 3.1)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Elasmobranchii
Order:	Squaliformes
Family:	Etmopteridae
Genus:	Etmopterus
Species:	E. evansi
Binomial name
Etmopterus evansi Last, G. H. Burgess & Séret, 2002
Range of the blackmouth lanternshark (in blue)

Taxonomy and phylogeny

The blackmouth lanternshark belongs to a subgroup of the genus Etmopterus that also includes the lined lanternshark, Etmopterus dislineatus. The genus name can be broken down into its Greek roots: "ethmos" refers to the sharks' ethmoid bone in the skull and "pteron" refers to sharks' fins. The species name evansi comes from the Australian fishery scientist, David Evans, who has spent years studying specimens of the species.

Distribution and habitat

Within the Indian ocean, the blackmouth lanternshark can be found in the continental slopes off the northwest coast of Western Australia. The species is also found in the continental slopes of the Arafura Sea south of the Tanimbar Islands in Indonesia. There are additional records of the species found off the coast of Papua New Guinea. Generally these lanternshark are found between 430 and 550 meters below sea level. More specifically, the sharks tend to inhabit shoals and reefs within these locations and depths. It is not known to have a preference for hard or soft substrate environments.

Description

The Blackmouth lanternshark is known to reach 30 cm in length. Knowledge on the species general description is limited due to its recent discovery and the limited samples currently being studied. Females tend to be larger than males, and the males are known to be mature at roughly 26 cm long. The longest individual found was 32 cm.

These lanternsharks are fusiform and approximately cylindrical in shape with a soft trunk. Compared to other species within the genus, evansi's head and snout are relatively short and its nostrils are relatively small. The species has relatively large, narrow eyes. Its mouth is narrow and moderately arched with four sets of functional teeth. The upper jaw contains three of the fours sets with small teeth usually having five cusps, and the lower jaw contains the fourth set with interlocking blade-like teeth with one cusp. The gills of the Blackmouth lanternfish are relatively large, approximately oblique, and roughly all the same size. Individuals have two dorsal fins, one pectoral fin, one pelvic fin and one caudal fin. The first fin is low and small compared to the second, and the pectoral fin is also relatively small. The caudal peduncle is long and thin. The caudal fin is very short, usually roughly the same size as the head.

Blackmouth lanternsharks have a light gray/brown dorsal half and a significantly darker ventral half separated by fine black lines. Individuals have denticles covering most of their body. There are a few bare spots but for the most part the denticles are dense and thin throughout, and are arranged in imperfect longitudinal rows. There are well defined melanophores and luminescent markings throughout the sharks' bodies as well.

Diet

The diet of the Blackmouth lanternshark has yet to be studied in depth but many species from the genus Etmopterus are known to feed on nekton such as krill, cephalopods, small crustaceans, and small teleost fish.

Behavior and ecology

The blackmouth lanternshark is ovoviviparous. The eggs are hatched within the female's uterus and sustained on a yolk sac until they are ready to hatch. The gestation period varies for many other species of Etmopterus but is generally longer than other sharks. These sharks require two reproductive seasons for one full reproductive cycle: one for reproductive organ development and gamete production and one for embryological development. Females within the Etmopterus genus produce anywhere from 2 to 20 young in one reproductive cycle. The Blackmouth lanternshark's mating behavior includes distinct pairing and a courtship embrace.

The blackmouth lanternshark is recognized as Least Concern in terms of conservation status. It is not known to be threatened by human activity due to its habitat.

References

1. ^ Kyne, Peter; Simpfendorfer, Colin (2010-03-09), "Deepwater Chondrichthyans", Marine Biology, CRC Press, pp. 37–113, doi:10.1201/9781420080483-c2 (inactive 2024-11-11), ISBN 978-1-4200-8047-6, retrieved 2022-04-19{{citation}}: CS1 maint: DOI inactive as of November 2024 (link)
2. Kyne, P.M.; Cavanagh, R.D. (2015). "Etmopterus evansi". IUCN Red List of Threatened Species. 2015: e.T41807A68622556. doi:10.2305/IUCN.UK.2015-4.RLTS.T41807A68622556.en. Retrieved 18 November 2021.
3. ^ Bernard, Last, P.R. Burgess, G.H. Séret (2002). Description of six new species of lantern-sharks of the genus Etmopterus (Squaloidea: Etmopteridae) from the Australasian region. OCLC 882933216.{{cite book}}: CS1 maint: multiple names: authors list (link)
4. Last, P. R. (2009). Sharks and rays of Australia. J. D. Stevens (2nd ed.). Cambridge, Mass.: Harvard University Press. ISBN 978-0-674-03411-2. OCLC 262430748.
5. ^ "Etmopterus evansi, Blackmouth lanternshark". www.fishbase.de. Retrieved 2022-04-19.
6. "Etmopterus evansi: Kyne, P.M. & Cavanagh, R.D." 2015-04-28. doi:10.2305/iucn.uk.2015-4.rlts.t41807a68622556.en. {{cite journal}}: Cite journal requires |journal= (help)
7. Hallett, Chris S.; Daley, Ross K. (2010-09-08). "Feeding ecology of the southern lanternshark (Etmopterus baxteri) and the brown lanternshark (E. unicolor) off southeastern Australia". ICES Journal of Marine Science. 68 (1): 157–165. doi:10.1093/icesjms/fsq143. ISSN 1095-9289.
8. Besnard, Lucien; Duchatelet, Laurent; Bird, Christopher S.; Le Croizier, Gaël; Michel, Loïc; Pinte, Nicolas; Lepoint, Gilles; Schaal, Gauthier; Vieira, Rui P.; Gonçalves, Jorge M.S.; Martin, Ulrich (April 2022). "Diet consistency but large-scale isotopic variations in a deep-sea shark: The case of the velvet belly lantern shark, Etmopterus spinax, in the northeastern Atlantic region and Mediterranean Sea". Deep Sea Research Part I: Oceanographic Research Papers. 182: 103708. Bibcode:2022DSRI..18203708B. doi:10.1016/j.dsr.2022.103708. ISSN 0967-0637. S2CID 246522469.
9. ^ Coelho, Rui; Erzini, Karim (August 2007). "Population parameters of the smooth lantern shark, Etmopterus pusillus, in southern Portugal (NE Atlantic)". Fisheries Research. 86 (1): 42–57. doi:10.1016/j.fishres.2007.04.006. ISSN 0165-7836.
10. IUCN (2019-07-01). "Etmopterus perryi: Pollom, R., Lasso-Alcalá, O., Mejía-Falla, P.A., Navia, A.F. & Herman, K.: The IUCN Red List of Threatened Species 2020: e.T60240A124455061". doi:10.2305/iucn.uk.2020-3.rlts.t60240a124455061.en. S2CID 242088588. {{cite journal}}: Cite journal requires |journal= (help)

• IUCN Red List least concern species
• Etmopterus
• Taxa named by Peter R. Last
• Taxa named by George H. Burgess
• Taxa named by Bernard Séret
• Fish described in 2002