''Triodon macropterus'' (

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often con ...

the threetooth puffer and the black-spot keeled pufferfish) is a tetraodontiform fish, the only living species in the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''Triodon'' and family Triodontidae. Other members of the family are known from fossils stretching back to the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

. The threetooth puffer was first scientifically described by

René Lesson René Primevère Lesson (20 March 1794 – 28 April 1849) was a French surgery, surgeon, natural history, naturalist, ornithologist, and herpetologist. Biography Lesson was born at Rochefort, Charente-Maritime, Rochefort, and entered the Naval ...

in 1831 and is recognizable for its large belly flap which has the ability to blend into the body when fully retracted.

Taxonomy

The threetooth puffer was first formally described in 1829 by the French

naturalist Natural history is a domain of inquiry involving organisms, including animals, fungi, and plants, in their natural environment, leaning more towards observational than experimental methods of study. A person who studies natural history is cal ...

with its type locality given as Mauritius. That same year

Georges Cuvier Jean Léopold Nicolas Frédéric, baron Cuvier (23 August 1769 – 13 May 1832), known as Georges Cuvier (; ), was a French natural history, naturalist and zoology, zoologist, sometimes referred to as the "founding father of paleontology". Cuv ...

formally proposed the new genus ''Triodon'' for the new species, also mentioning ''Triodon bursarius'', although this is now regarded as a

synonym A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

of ''T. macropterus''. The 5th edition of ''

Fishes of the World ''Fishes of the World'' is a standard reference for the systematics of fishes. It was first written in 1976 by the American ichthyologist Joseph S. Nelson (1937–2011). Now in its fifth edition (2016), the work is a comprehensive overview of t ...

'' classifies this taxon within the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

family Triodontidae, which it places within the monotypic suborder Triodontoidei within the order Tetraodontiformes.

Etymology

The name ''Triodon macropterus'' comes from the

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

(, meaning 'three') and (or , , meaning 'tooth'), and refers to the three fused teeth that make up a beak-like structure.

Distribution and ecology

The threetooth puffer is native to the

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

, where it is found mainly around Australia and off the coast of Asia at depths from . Its habitat is

pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

, consisting of

continental shelves A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

slopes In mathematics, the slope or gradient of a Line (mathematics), line is a number that describes the direction (geometry), direction of the line on a plane (geometry), plane. Often denoted by the letter ''m'', slope is calculated as the ratio of t ...

seamount A seamount is a large submarine landform that rises from the ocean floor without reaching the water surface (sea level), and thus is not an island, islet, or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly a ...

s, and knolls.

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 Foraminifera ( ; Latin for "hole bearers"; informally called "forams") are unicellular organism, single-celled organisms, members of a phylum or class (biology), class of Rhizarian protists characterized by streaming granular Ectoplasm (cell bio ...

echinoids Sea urchins or urchins () are echinoderms in the class (biology), class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal zone to deep seas of . They typically have a globular body cove ...

, and

sponge Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and a ...

s. The intestinal tract of the threetooth puffer (the

esophagus The esophagus (American English), oesophagus (British English), or œsophagus (Œ, archaic spelling) (American and British English spelling differences#ae and oe, see spelling difference) all ; : ((o)e)(œ)sophagi or ((o)e)(œ)sophaguses), c ...

stomach The stomach is a muscular, hollow organ in the upper gastrointestinal tract of Human, humans and many other animals, including several invertebrates. The Ancient Greek name for the stomach is ''gaster'' which is used as ''gastric'' in medical t ...

, and

intestines The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascular system. ...

) is lined with several papillae, protrusions of the gut lumen. After the stomach, the tract branches off into a specialized sac-like compartment called Tyler's Pouch. Within the Tyler's Pouch the papillae are much larger in size and number compared to those prior. The role and function of Tyler's Pouch is largely unknown.

Adult characteristics

The threetooth puffer reaches a maximum length of . 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. The flap is inflated by rotating the shaft-like

pelvis The pelvis (: pelves or pelvises) is the lower part of an Anatomy, anatomical Trunk (anatomy), trunk, between the human abdomen, abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also c ...

downwards, exposing a black eye-spot contoured with yellow. This makes the animal appear much larger to predators, and less likely to be eaten. When danger is not present, the flap is retracted seamlessly into the body and the eye-spot is not visible. 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. 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. The threetooth puffer has ribs, a beak, and no pelvic fins which are all characteristics of

tetraodontiformes Tetraodontiformes (), also known as the Plectognathi, is an order of ray-finned fishes which includes the pufferfishes and related taxa. This order has been classified as a suborder of the order Perciformes, although recent studies have found ...

. Adult scales have a rhombic base, and each has a median ridge from which several spines protrude. 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 Jean Léopold Nicolas Frédéric, baron Cuvier (23 August 1769 – 13 May 1832), known as Georges Cuvier (; ), was a French natural history, naturalist and zoology, zoologist, sometimes referred to as the "founding father of paleontology". Cuv ...

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

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. The head of the specimen makes up 45% of the length of its body, and its eyes make up 18% of its body length. As a juvenile, the pelvic bone is continuing to develop within the rotund belly. Juveniles have unicuspid scales, tricuspid scales, and pentacuspid scales.

Danger to humans

''Triodon macropterus'' is harmless to humans unless eaten, at which point the species is considered poisonous.

References

{{Taxonbar, from=Q1258238 Triodontidae Tetraodontiformes Fish described in 1831 Taxa named by René Lesson Taxa named by Georges Cuvier