Threetooth puffer

{{Short description|Species of fish}} {{Speciesbox | fossil_range = {{Fossil range|54|0|Early Eocene to present}} | image = Triodon macropterus JNC2989.JPG | image_caption = ''Triodon macropterus'', with extended belly flap | greatgrandparent_authority = | grandparent_authority = Bleeker, 1859<ref name = VDLEF>{{cite journal | author1 = Richard van der Laan | author2 = William N. Eschmeyer | author3 = Ronald Fricke | name-list-style = amp |year=2014 | title = Family-group names of recent fishes | url = https://biotaxa.org/Zootaxa/article/view/zootaxa.3882.1.1/10480 | journal = Zootaxa | volume = 3882 | issue = 2 | pages = 1–230| doi = 10.11646/zootaxa.3882.1.1 | pmid = 25543675 | doi-access = free }}</ref> | parent_authority = Cuvier, 1829 | taxon = Triodon macropterus | authority = Lesson, 1829 | display_parents = 3 | synonyms = *''Triodon bursarius'' Cuvier, 1829 }}

'''''Triodon macropterus''''' (common name the '''threetooth puffer''' and the '''black-spot keeled pufferfish''') is a tetraodontiform fish, the only living species in the genus ''Triodon'' and family '''Triodontidae'''.<ref name="Matsuura2014">{{cite journal|author=Matsuura, K. |year=2014|title= Taxonomy and systematics of tetraodontiform fishes: a review focusing primarily on progress in the period from 1980 to 2014|journal=Ichthyological Research|volume= 62 |issue=1|pages= 72–113|doi=10.1007/s10228-014-0444-5 |doi-access=free}}</ref><ref name="smith3">{{cite web|author=Gomon, M.F. |author2= Bray, D.J. |year=2011|title= Threetooth Puffer, ''Triodon macropterus''|url=https://fishesofaustralia.net.au/home/species/4195 |website=Fishes of Australia}}</ref> Other members of the family are known from fossils stretching back to the Eocene.<ref name="EoF3">{{cite book|author1=Matsuura, K.|title=Encyclopedia of Fishes|author2=Tyler, J.C.|publisher=Academic Press|year=1998|isbn=0-12-547665-5|editor=Paxton, J.R.|location=San Diego|page=230|editor2=Eschmeyer, W.N.|name-list-style=amp}}</ref> The threetooth puffer was first scientifically described by René Lesson in 1831 and is recognizable for its large belly flap which has the ability to blend into the body when fully retracted.<ref name="Matsuura2014" /><ref name="smith3" />

==Taxonomy== The threetooth puffer was first formally described in 1829 by the French naturalist René Lesson with its type locality given as Mauritius.<ref name = CofF>{{Cof genus|genus=Triodon|access-date=27 August 2024}}</ref> That same year Georges Cuvier formally proposed the new genus ''Triodon'' for the new species, also mentioning ''Triodon bursarius'', although this is now regarded as a synonym of ''T. macropterus''.<ref name = CofF/><ref name = CofF2>{{Cof family|family=Triodontidae}}</ref> The 5th edition of ''Fishes of the World'' classifies this taxon within the monotypic family Triodontidae, which it places within the monotypic suborder Triodontoidei within the order Tetraodontiformes.<ref name = Nelson5>{{BioRef |fotw5 |pages=518–526}}</ref>

The family was formerly placed in its own suborder, Triodontoidei. However, more recent taxonomic studies have found it to be closely related to the pufferfish, molas, and porcupinefish, and it is now placed in the suborder Tetraodontoidei with those families.'''<ref name=":13">{{Cite web |last1=Fricke |first1=R. |last2=Eschmeyer |first2=W. N. |last3=Van der Laan |first3=R. |date=2025 |title=ESCHMEYER'S CATALOG OF FISHES: CLASSIFICATION |url=https://www.calacademy.org/eschmeyers-catalog-of-fishes-classification |access-date= |website=California Academy of Sciences |language=en}}</ref>'''

=== Evolution === ''Triodon'' is an ancient genus known since the Early Eocene, when the earliest known species, the extinct †''Triodon antiquus'' Leriche, 1905 has been identified from the London Clay of England and the Nanjemoy Formation of Maryland, US. This species closely resembles the modern ''Triodon macropterus''.<ref>{{Cite journal |last=Weems |first=Robert E. |date=2021 |title=ADDITIONS TO THE BONY FISH FAUNA FROM THE EARLY EOCENE NANJEMOY FORMATION OF MARYLAND AND VIRGINIA (U.S.A) |url=https://www.researchgate.net/publication/348579659_The_Mosasaur_The_Journal_of_the_Delaware_Valley_Paleontological_Society_Editor_Layout_Editor_ADDITIONS_TO_THE_BONY_FISH_FAUNA_FROM_THE_EARLY_EOCENE_NANJEMOY_FORMATION_OF_MARYLAND_AND_VIRGINIA_USA |journal=The Mosasaur : The Journal of the Delaware Valley Paleontological Society |volume=XI |pages=117-152}}</ref><ref name=":3">{{Cite journal |last=Close |first=Roger A. |last2=Johanson |first2=Zerina |last3=Tyler |first3=James C. |last4=Harrington |first4=Richard C. |last5=Friedman |first5=Matt |date=2016 |title=Mosaicism in a new Eocene pufferfish highlights rapid morphological innovation near the origin of crown tetraodontiforms |url=https://onlinelibrary.wiley.com/doi/abs/10.1111/pala.12245 |journal=Palaeontology |language=en |volume=59 |issue=4 |pages=499–514 |doi=10.1111/pala.12245 |issn=1475-4983|doi-access=free }}</ref> Also known from the London Clay is the extinct genus †''Ctenoplectus'' Close ''et al''., 2016, which is thought to be the sister genus to ''Triodon''.<ref name=":3" />

== Etymology == The name ''Triodon macropterus'' comes from the Ancient Greek {{wikt-lang|grc|τρι-}} ({{grc-transl|τρι-}}, meaning 'three') and {{wikt-lang|grc|ὀδούς}} (or {{wikt-lang|grc|ὀδών}}, {{grc-transl|ὀδούς, ὀδών}}, meaning 'tooth'), and refers to the three fused teeth that make up a beak-like structure.<ref name="smith3" />

== Distribution and ecology == The threetooth puffer is native to the Indo-Pacific, where it is found mainly around Australia and off the coast of Asia at depths from {{cvt|30-300|m|ft|-1}}.<ref name="smith3" /><ref name=":0">{{FishBase |Triodon|macropterus |month= March 2|year=2021}}</ref><ref name="FishBase2">{{FishBase|genus=Triodon|species=macropterus|month=February|year=2015}}</ref><ref>''COPEPEDIA Molecular Info for Syntripsa Flavichela : T4015260 : Species'', updated 11 Nov. 2020, www.st.nmfs.noaa.gov/nauplius/media/copepedia/taxa/T4015260/html/primerframe.html.</ref><ref name=":2">{{cite journal|author=Yamanoue, Y. |display-authors=et al. |date=19 July 2008|title=A New Perspective on Phylogeny and Evolution of Tetraodontiform Fishes (Pisces: Acanthopterygii) Based on Whole Mitochondrial Genome Sequences: Basal Ecological Diversification?|journal=BMC Evolutionary Biology|volume=8|issue=1 |page=212 |doi=10.1186/1471-2148-8-212 |doi-access=free |pmid=18638411 |pmc=2500030 |bibcode=2008BMCEE...8..212Y |via=BioMedCentral}}</ref> Its habitat is pelagic, consisting of continental shelves, slopes, seamounts, and knolls.<ref>{{cite WoRMS|author=Bailly, Nicolas|year=2014|title=''Triodon macropterus'' Lesson, 1831|id=205828|access-date= March 12, 2021}}</ref><ref name=":2" />

== Diet and digestion == Little is known about the diet of the threetooth puffer. However, a dissection of the stomach of a caught juvenile specimen uncovered traces of mysid crustacean, foraminifera, echinoids, and sponges.<ref name=":1">{{cite journal|author=Johnson, G.D.|author2= Britz, R. |date=29 January 2005 |title=A Description of the Smallest ''Triodon'' on Record (Teleostei: Tetraodontiformes: Triodontidae) |journal=Ichthyological Research|volume= 52|issue= 2|pages= 176–181|doi= 10.1007/s10228-005-0271-9 |bibcode= 2005IchtR..52..176J }}</ref>

The intestinal tract of the threetooth puffer (the esophagus, stomach, and intestines) is lined with several papillae, protrusions of the gut lumen.<ref name=":1" /> After the stomach, the tract branches off into a specialized sac-like compartment called Tyler's Pouch.<ref name=":1" /> Within the Tyler's Pouch the papillae are much larger in size and number compared to those prior.<ref name=":1" /> The role and function of Tyler's Pouch is largely unknown.<ref name=":1" />

== Adult characteristics == The threetooth puffer reaches a maximum length of {{cvt|54|cm|in}}.<ref name=":0" /> Its body is yellowish-brown with a white belly flap as large as or larger than its body which it inflates with seawater when threatened.<ref name="smith3" /> The flap is inflated by rotating the shaft-like pelvis downwards, exposing a black eye-spot contoured with yellow.<ref name="EoF3" /><ref name=":0" /><ref>{{Cite journal |last1=Bemis |first1=Katherine E. |last2=Tyler |first2=James C. |last3=Kaneko |first3=Atsushi |last4=Matsuura |first4=Keiichi |last5=Murakumo |first5=Kiyomi |last6=Espíndola |first6=Vinicius C. |last7=Justine |first7=Jean-Lou |last8=Tyler |first8=Diane M. |last9=Girard |first9=Matthew G. |last10=Bemis |first10=William E. |date=2023-04-18 |title=Pelvic-Fan Flaring and Inflation in the Three-Tooth Puffer, ''Triodon macropterus'' (Tetraodontiformes: Triodontidae), with Additional Observations on Their Behavior in Captivity |journal=Ichthyology & Herpetology |volume=111 |issue=2 |doi=10.1643/i2022022 |issn=2766-1512|doi-access=free }}</ref> This makes the animal appear much larger to predators, and less likely to be eaten.<ref name="EoF3" /> When danger is not present, the flap is retracted seamlessly into the body and the eye-spot is not visible.<ref name="smith3" />

The head of an adult threetooth puffer makes up approximately 30.6% of the length of its body, and the eyes make up about 7.5% of its body length.<ref name=":1" /> The upper jaw is composed of two dental plates while the teeth on the lower jaw protrude from a single dental plate, resulting in a beak.<ref name="smith3" />

The threetooth puffer has ribs, a beak, and no pelvic fins which are all characteristics of tetraodontiformes.<ref name=":2" />

Adult scales have a rhombic base, and each has a median ridge from which several spines protrude.<ref name=":1" /><gallery> File:Triodon macropterus JNC2989 Fresh.JPG|Living specimen, belly flap half extended File:MHNT - Triodon bourse.jpg|Desiccated museum specimen File:Triodon.jpg|Illustrated specimen by Cuvier File:Triodon macropterus JNC2989 Eye.JPG|Eye File:Triodon macropterus JNC2989 Teeth.JPG|Beak-like structure composed of fused teeth File:Triodon macropterus JNC2989 Spot.JPG|Lateral eye-spot </gallery>

== Juvenile characteristics == The smallest ''Triodon macropterus'' specimen on record measures 20mm long and belongs to the ichthyological section of the Muséum Nationale d'Histoire Naturelle in Paris.<ref name=":1" /> The head of the specimen makes up 45% of the length of its body, and its eyes make up 18% of its body length.<ref name=":1" /> As a juvenile, the pelvic bone is continuing to develop within the rotund belly.<ref name=":1" />

Juveniles have unicuspid scales, tricuspid scales, and pentacuspid scales.<ref name=":1" />

== Danger to humans == ''Triodon macropterus'' is harmless to humans unless eaten, at which point the species is considered poisonous.<ref name="smith3" /><ref name=":0" />

==References== {{Reflist}}

Category:Triodontidae Category:Tetraodontiformes Category:Fish described in 1831 Category:Taxa named by René Lesson Category:Taxa named by Georges Cuvier