{{Short description|Species of shark}} {{Speciesbox | image = Etmopterus lucifer (Blackbelly lanternshark).gif | image_caption = Drawing by Dr Tony Ayling | status = LC | status_system = IUCN3.1 | status_ref=<ref name="iucn status 18 November 2021">{{cite iucn |author=Finucci, B. |author2=Ebert, D.A. |author3=Schaaf-Da Silva, A |date=2018 |title=''Etmopterus lucifer'' |volume=2018 |article-number=e.T161517A889953 |doi=10.2305/IUCN.UK.2018-2.RLTS.T161517A889953.en |access-date=18 November 2021}}</ref> | genus = Etmopterus | species = lucifer | authority = [[David Starr Jordan|D. S. Jordan]] & [[John Otterbein Snyder|Snyder]], 1902 | range_map = Etmopterus lucifer distmap.png | range_map_caption = Range of the blackbelly lanternshark (in blue) }} {{Portal|Sharks}}
The '''blackbelly lanternshark''' or '''lucifer shark''' ('''''Etmopterus lucifer''''') is a shark of the [[Family (taxonomy)|family]] [[Etmopteridae]] found around the world in tropical and temperate seas at depths between 150 and 1,250 meters{{snd}}the [[mesopelagic zone]].<ref name=":0">{{Cite web|url=https://www.fishbase.de/summary/Etmopterus-lucifer.html|title=Etmopterus lucifer Jordan & Snyder, 1902 Blackbelly lanternshark|last1=Carpenter|first1=Kent E.|last2=Capuli|first2=Estelita Emily|date=2019|website=Fishbase|access-date=19 January 2019}}</ref> Compared to other mesopelagic fish predators and invertebrates, the blackbelly lanternshark is thought to reside in shallower, more southern waters.<ref name=":32" /> ''E. lucifer'' can reach up to 47 centimeters in length<ref name=":0" /> and consumes mesopelagic [[cephalopod]]s, fish, and crustaceans.<ref name=":2">{{Cite book|title=The fishes of New Zealand|last1=Roberts|first1=Clive|last2=Stewart|first2=A. L.|last3=Struthers|first3=Carl D.|last4=Barker|first4=Jeremy|last5=Kortet|first5=Salme|last6=Freeborn|first6=Michelle|publisher=Te Papa Press|year=2015|isbn=978-0-9941041-6-8|volume=2|location=Wellington, New Zealand|page=143|oclc=908128805}}</ref> Blackbelly lanternsharks are [[bioluminescence|bioluminescent]], using hormone controlled mechanisms to emit light through ventral photogenic organs called photophores<ref name=":5">{{Cite journal |last1=Duchatelet |first1=Laurent |last2=Claes |first2=Julien M. |last3=Delroisse |first3=Jérôme |last4=Flammang |first4=Patrick |last5=Mallefet |first5=Jérôme |date=December 2021 |title=Glow on Sharks: State of the Art on Bioluminescence Research |journal=Oceans |language=en |volume=2 |issue=4 |pages=822–842 |doi=10.3390/oceans2040047 |doi-access=free |issn=2673-1924|hdl=2078.1/255940 |hdl-access=free }}</ref><ref name=":02" /> and are presumed to be [[Ovoviviparity|ovoviviparous]].<ref name=":0" /> The blackbelly lanternshark has been classified as "Not Threatened" within the New Zealand Threat Classification System.<ref name=":3">{{Cite book |last1=Duffy |first1=Clinton A. J. |url=https://www.doc.govt.nz/globalassets/documents/science-and-technical/nztcs23entire.pdf |title=Conservation status of New Zealand chondrichthyans (chimaeras, sharks and rays), 2016 |last2=Francis |first2=Malcolm |last3=Dunn |first3=M. R. |last4=Finucci |first4=Brit |last5=Ford |first5=Richard |last6=Hitchmough |first6=Rod |last7=Rolfe |first7=Jeremy |publisher=Department of Conservation |year=2018 |isbn=978-1-988514-62-8 |location=Wellington, New Zealand |page=10 |oclc=1042901090}}</ref>
== Distribution and habitat == ''Etmopterus lucifer'' is prevalent in New Zealand's deep waters, most commonly found on the south Chatham Rise, with the greatest occurrence recorded at around 500 meters in depth.<ref name=":32">{{Cite journal |last1=Dunn |first1=Matthew R. |last2=Stevens |first2=Darren W. |last3=Forman |first3=Jeffrey S. |last4=Connell |first4=Amelia |date=2013-03-25 |title=Trophic Interactions and Distribution of Some Squaliforme Sharks, Including New Diet Descriptions for Deania calcea and Squalus acanthias |journal=PLOS ONE |language=en |volume=8 |issue=3 |article-number=e59938 |doi=10.1371/journal.pone.0059938 |doi-access=free |issn=1932-6203 |pmc=3607562 |pmid=23536896|bibcode=2013PLoSO...859938D }}</ref> ''E. lucifer'' is categorized as a mesopelagic fish, preferring shallower and more southern habitats.<ref name=":32" /> Between 1992 and 2010, a significant increase in ''E. lucifer'' biomass was observed along the east coast of the North Island.<ref name=":32" /> In New Zealand's deep-sea trawl fisheries, ''Etmopterus lucifer,'' alongside the ''[[Southern lanternshark|Etmopterus granulosus]]'', constitutes the predominant by-catch species.<ref name=":02" />
== Taxonomy == ''Etmopterus lucifer'' was first discovered and scientifically documented by David Starr Jordan & John Otterbein Snyder in 1902 off the east coast of Honshu, Japan.<ref>{{Cite journal |last1=Jordan |first1=David Starr |last2=Snyder |first2=John Otterbein |date=1902 |title=Descriptions of two new species of squaloid sharks from Japan |url=https://repository.si.edu/handle/10088/13669 |journal=Proceedings of the United States National Museum |language=en |volume=25 |issue=1279 |pages=79–81 |doi=10.5479/si.00963801.25-1279.79|hdl=10088/13669 |url-access=subscription }}</ref> It is a member of the family ''[[Etmopteridae]]'' which is in the order ''[[Squaliformes]].''<ref name=":1" />
* Additional phylogenetic information can be found here <ref>{{Cite journal |last1=Straube |first1=Nicolas |last2=Iglésias |first2=Samuel P. |last3=Sellos |first3=Daniel Y. |last4=Kriwet |first4=Jürgen |last5=Schliewen |first5=Ulrich K. |date=2010-09-01 |title=Molecular phylogeny and node time estimation of bioluminescent Lantern Sharks (Elasmobranchii: Etmopteridae) |url=https://www.sciencedirect.com/science/article/pii/S1055790310002101 |journal=Molecular Phylogenetics and Evolution |volume=56 |issue=3 |pages=905–917 |doi=10.1016/j.ympev.2010.04.042 |pmid=20457263 |issn=1055-7903|url-access=subscription }}</ref>
== Anatomy and morphology == [[File:Blackbelly Lantern Shark.jpg|thumb|Specimen of ''Etmopterus lucifer'' Jordan & Snyder, 1902 - The Trustees of the Natural History Museum, London, United Kingdom]] ''Etmopterus lucifer'' has a slender body with brown coloration on the top and black coloration on the bottom.<ref name=":18">{{Cite book |last1=Dando |first1=Marc |title=A Pocket Guide to Sharks of the World: Second Edition |last2=Ebert |first2=David A. |last3=Fowler |first3=Sarah |date=2021 |publisher=Princeton University Press |isbn=978-0-691-21874-8 |doi=10.2307/j.ctv1cmsmwn.12|jstor=j.ctv1cmsmwn }}</ref> ''E. lucifer'' is shown to have a higher amount of pores{{snd}}associated with sensory [[ampullae of Lorenzini]]{{snd}}on its ventral side than dorsal side, meaning the species likely closes in on prey from above.<ref name=":7">{{Cite journal |last1=Staggl |first1=Manuel Andreas |last2=Ruthensteiner |first2=Bernhard |last3=Straube |first3=Nicolas |date=May 2023 |title=Head anatomy of a lantern shark wet-collection specimen (Chondrichthyes: Etmopteridae) |journal=Journal of Anatomy |language=en |volume=242 |issue=5 |pages=872–890 |doi=10.1111/joa.13822 |issn=0021-8782 |pmc=10093163 |pmid=36695312}}</ref> Black markings are also featured around the pelvic, or ventral, fins and at the base of the caudal, or tail, fin. The blackbelly lanternshark has two dorsal fins,<ref name=":1">{{Cite web |title=Etmopterus lucifer, Blackbelly lanternshark |url=https://fishbase.mnhn.fr/summary/681 |access-date=2024-03-27 |website=fishbase.mnhn.fr}}</ref> the second of which is larger, and a caudal, or tail, fin, which is relatively long.<ref name=":18" /> The interdorsal space is short.<ref name=":6">{{Cite book |last1=Ebert |first1=David A. |title=Sharks of the World: A Complete Guide |last2=Dando |first2=Marc |last3=Fowler |first3=Sarah |date=2021 |publisher=Princeton University Press |isbn=978-0-691-20599-1 |doi=10.2307/j.ctv1574pqp.13|jstor=j.ctv1574pqp }}</ref> ''E. lucifer'' has relatively long gills, as well as five [[branchial arch]]es.<ref name=":7" /> Along the side of the body, from its snout to its tail fin, are rows of hook-shaped [[Denticle (tooth feature)|denticles]].<ref name=":18" /><ref name=":7" /> The lower jaw contains between 29 and 39 teeth that have one cusp, while the upper jaw contains between 21 and 26 teeth that have up to three cusps.<ref name=":6" /><ref name=":8">Compagno, L.J.V. (1984). "FAO species catalogue. Vol. 4. Sharks of the world. An annotated and illustrated catalogue of shark species known to date. Part 1. Hexanchiformes to Lamniformes." FAO Fish Synop., no. 125, vol. 4, part 1, p. 79. https://www.iucnssg.org/uploads/5/4/1/2/54120303/fao_species_catalogue_for_fishery_purposes_-_1984_-_sharks_of_the_world_-_an_annotated_and_illustrated_catalogue_of_shark_species_known_to_date_-_part_1_-_hexanchiformes_to_lamniformes.pdf</ref> Teeth are around 2 mm in length.<ref name=":6" />
The maximum length of ''E. lucifer'' is about 47 cm.<ref name=":6" /> Males range from 29 to 42 cm, while females are 34 cm or more in length.<ref name=":6" /><ref name=":8" />
''Etmopterus lucifer'' has a wide and protruding [[Rostrum (anatomy)|rostrum]], with large nasal capsules and rostral [[Antorbital fenestra|fenestrae]].<ref name=":7" /> As a deep-sea species, ''E. lucifer'' has a large eye diameter, which can result in higher sensitivity to penetrating light and bioluminescence.<ref name=":7" /> A translucent region in the upper eye orbit of ''E. lucifer'' can potentially help the species detect camouflage.<ref name=":4" /> E. lucifer has high [[Rod cell|rod]] density in the nasal area of the eye, that allow the species to detect bioluminescent markings of other individuals and adjust to low-light conditions.<ref name=":4" />
=== Bioluminescence === Three families of [[shark]] are known to contain [[Bioluminescence|bioluminescent]] species including ''[[Etmopteridae]]'', ''[[Dalatiidae]]'', and ''[[Somniosidae]]'' with recent research suggesting that the evolution of bioluminescence in sharks occurred once.<ref name=":5" /> Like all bioluminescent sharks, blackbelly lanternsharks are covered in small photogenic organs called [[photophore]]s. A photophore is composed of [[photocyte]]s, the cells where bioluminescent reactions take place, arranged in a cup shaped sheath and covered with lens cells. An iris-like structure (ILS) is located underneath the lens of the photophore and can open and close to release light.<ref name=":02">{{Cite journal |last1=Mallefet |first1=Jérôme |last2=Stevens |first2=Darren W. |last3=Duchatelet |first3=Laurent |date=2021 |title=Bioluminescence of the Largest Luminous Vertebrate, the Kitefin Shark, Dalatias licha: First Insights and Comparative Aspects |journal=Frontiers in Marine Science |volume=8 |doi=10.3389/fmars.2021.633582 |doi-access=free |issn=2296-7745|hdl=2078.1/244143 |hdl-access=free }}</ref> Photophores are located across the body of ''E. lucifer'' in distinct arrangements, but are found in much higher density on the ventral side of the shark where they are oriented downward.<ref name=":02" /><ref name=":22">{{Cite journal |last1=Claes |first1=Julien M. |last2=Nilsson |first2=Dan-Eric |last3=Straube |first3=Nicolas |last4=Collin |first4=Shaun P. |last5=Mallefet |first5=Jérôme |date=2014-03-10 |title=Iso-luminance counterillumination drove bioluminescent shark radiation |journal=Scientific Reports |language=en |volume=4 |issue=1 |page=4328 |doi=10.1038/srep04328 |pmid=24608897 |pmc=3948070 |bibcode=2014NatSR...4E4328C |issn=2045-2322}}</ref> ''E. lucifer'' also displays photophores in clade specific lateral markings as well as along its pectoral fins and [[clasper]]s.<ref name=":02" />
Because of the ventral arrangement of light emitting organs on the body of ''E. lucifer'' and other bioluminescent sharks, researchers have hypothesized that bioluminescence evolved as a form of [[cryptic coloration]], allowing blackbelly lanternsharks to blend into the residual downwelling sunlight of their midwater environment when viewed from below.<ref name=":5" /><ref name=":02" /> This form of camouflage protects sharks from predators at deeper depths. Research with a related species of shark, ''[[Velvet belly lanternshark|Etmopterus spinax]]'', has shown that ''Etmopteridae'' do not significantly alter the intensity of their luminescence and suggests that lanternsharks engage in daily [[Diel vertical migration|vertical migration]] to follow an [[Isolume|iso-lume]].<ref name=":5" /><ref name=":02" /> Due to lateral bioluminescent markings on the blackbelly lanternshark forming a narrow stripe along the side of the organism that could be recognizable to predators, it has been suggested that this species experiences a more relaxed threat of predation.<ref name=":22" /><ref name=":02" /> Instead, researchers have hypothesized that because these markings are distinct to the ''E. lucifer'' clade, they might aid in recognition and communication between conspecifics, and be a form of bioluminescent signaling.<ref name=":02" /><ref name=":22" /><ref name=":4">{{Cite journal |last1=Claes |first1=Julien M. |last2=Partridge |first2=Julian C. |last3=Hart |first3=Nathan S. |last4=Garza-Gisholt |first4=Eduardo |last5=Ho |first5=Hsuan-Ching |last6=Mallefet |first6=Jérôme |last7=Collin |first7=Shaun P. |date=2014-08-06 |title=Photon Hunting in the Twilight Zone: Visual Features of Mesopelagic Bioluminescent Sharks |journal=PLOS ONE |language=en |volume=9 |issue=8 |article-number=e104213 |doi=10.1371/journal.pone.0104213 |doi-access=free |issn=1932-6203 |pmc=4123902 |pmid=25099504|bibcode=2014PLoSO...9j4213C }}</ref>
Bioluminescence in blackbelly lanternsharks and other ''Etmopteridae'' sharks has been found to be controllable through manipulation of hormones including [[melatonin]] (MT), [[Alpha-Melanocyte-stimulating hormone|α-melanocyte-stimulating hormone]] (α-MSH), and [[adrenocorticotropic hormone]] (ACTH).<ref name=":02" /> MT was found to induce light emission in the photophores of ''E. lucifer'', a process that simultaneously occurred with the opening of the iris-like structure (ILS) leading researchers to conclude that both the bioluminescent chemical reaction occurring in photocytes and the ILS appear to be involved in the control of light emissions. α-MSH and ACTH were both found to decrease light emissions in the photophores of ''E. lucifer''.<ref name=":02" /> Additional information on the biochemical mechanism for bioluminescence in sharks is still being researched. Studies have attempted to link bioluminescence to known [[luciferin]]s, chemicals that produced light when oxidized by a [[luciferase]] enzyme, but it has been suggested that a novel photoprotein or luciferase might be present in sharks.<ref name=":5" />
== Biology and ecology == Blackbelly lanternsharks are presumed to be [[Ovoviviparity|ovoviviparous]].<ref name=":0" />
The diet of ''Etmopterus lucifer'' is generally characterized as consisting of squids and myctophids<ref name=":11">{{Cite thesis |title=Demographics of Etmopterus lucifer (Lucifer dogfish) |url=https://openaccess.wgtn.ac.nz/articles/thesis/Demographics_of_Etmopterus_lucifer_Lucifer_dogfish_/17013593/1 |publisher=Open Access Te Herenga Waka-Victoria University of Wellington |date=2015-01-01 |degree=thesis |language=en |first=Annie Rose |last=Galland}}</ref> (lanternfishes) with slight regional differences. Populations found near Australia have been found to consume a variety of teleost, with the most common being myctophids, while also being known to feed on crustaceans and squids.<ref name=":32" /> Populations in Japan have been found to consume euphausiids as part of their regular diet instead of crustaceans, though they still retain squids, albeit mesopelagic squids, and myctophids as part of their feeding regime.<ref name=":32" /> In Southern Africa, ''E. lucifer'' has maintained myctophids in their diet, however, studies have found that they prefer to also hunt pelagic cephalopods in contrast to their regional counterparts that typically prefer squids in specific.<ref name=":32" />
''Etmopterus lucifer'' is thought to attract its prey through the use of the photophores primarily found concentrated on its body that contribute to its cryptic coloration that provides both camouflage from predators and prey alike.<ref name=":5" /><ref name=":02" /> ''Etmopterus lucifer'' prey detection can be attributed to its theorized electro-sensory sensitivity.<ref name=":7" /> Blackbelly lanternsharks have been found to have a substantial number of Ampullae of Lorenzini, which contribute to the detection of electrical fields (and resultantly prey), and through the use of ducts and pores, blackbelly lanternsharks can reduce the hindrance experienced as the signal moves along by having the destination be a synapse with a large diameter.<ref name=":7" /> Through this reduction it is thought that the blackbelly lanternshark increases its overall sensitivity, allowing it to better detect faster prey.<ref name=":7" /> Once the prey is within distance, the blackbelly lanternshark then utilizes its jaw to consume its prey entirely. It is thought that the separation of the suborbital muscle from the mandibular adductor muscle observed within this species of lanternsharks is thought to aid in the further extension of the mouth and thus permit the lanternshark to consume larger prey.<ref name=":7" /> Labial cartilage present in ''E. lucifer'' has also been studied and found to aid in minor suction force which possibly assist with its feeding.<ref>{{Cite journal |last=Klimpfinger |first=Claudia |date=December 3, 2023 |title=Morphological Variability and Function of Labial Cartilages in Sharks (Chondrichthyes, Elasmobranchii) |journal=Biology |volume=12 |issue=12 |page=1486 |doi=10.3390/biology12121486 |pmc=10741050 |pmid=38132312 |doi-access=free}}</ref>
== Conservation status == In June 2018, the New Zealand [[Department of Conservation (New Zealand)|Department of Conservation]] classified the blackbelly lanternshark as "Not Threatened" with the qualifiers "Data Poor" and "Secure Overseas" under the [[New Zealand Threat Classification System]].<ref name=":3" /> The species has low fishing mortality, as its small size may allow evasion of nets and trawls.<ref>{{Cite web |last1=Finucci |first1=B. |last2=Ebert |first2=D.A. |last3=Schaaf-Da Silva |first3=A. |date=2018 |title=Etmopterus lucifer |url=https://www.iucnredlist.org/species/161517/889953 |website=The IUCN Red List of Threatened Species}}</ref>
==References== {{Reflist}}
{{Selachimorpha|D.}} {{Taxonbar|from=Q3234649}}
[[Category:Etmopterus]] [[Category:Taxa named by David Starr Jordan]] [[Category:Taxa named by John Otterbein Snyder]] [[Category:Fish described in 1902]]