|Threetooth puffer, Triodon macropterus, with extended belly flap|
G. Cuvier, 1829
The threetooth puffer, Triodon macropterus, is a tetraodontiform fish, the only living species in the genus Triodon and family Triodontidae. Other members of the family are known from fossils stretching back to the Eocene.
It is native to the Indo-Pacific, where found at depths to 300 m (980 ft). Its name comes from the Greek tria meaning "three" and odous meaning "tooth", and refers to the three fused teeth making up a beak-like structure.
The threetooth puffer reaches a maximum length of 54 cm (21 in). It has a distinctive shape, with a huge belly flap as large as or larger than its body; it inflates this with seawater when threatened. The flap bears an eye-spot, and is inflated by rotating the shaft-like pelvis downwards. This makes the animal appear much larger to predators, and less likely to be eaten.
The threetooth puffer is also known as the Black-spot Keeled Pufferfish, and was first scientifically described by Lesson in 1831. 
Drawing by Cuvier
- Keiichi, Matsura & Tyler, James C. (1998). Paxton, J.R. & Eschmeyer, W.N., ed. Encyclopedia of Fishes. San Diego: Academic Press. p. 230. ISBN 0-12-547665-5.
- Froese, Rainer and Pauly, Daniel, eds. (2011). "Triodon macropterus" in FishBase. August 2011 version.
- Martin F. Gomon & Dianne J. Bray (2011) Threetooth Puffer, Triodon macropterus, Fishes of Australia. Retrieved 29 Sep 2014.