Temporal range: 55–0Ma
Early Eocene to Present
Fish of the genus Diodon have;
- two-rooted, moveable spines (actually modified scales) distributed over their bodies.
- beak-like jaws, used to crush their hard-shelled prey (crustaceans and molluscs).
- Like true pufferfishes of the related family Tetraodontidae, porcupinefishes can inflate themselves. Once inflated, a porcupinefish's erected spines stand perpendicular to the skin, whereupon they then pose a major difficulty to their predators: a large porcupinefish that is fully inflated can choke a shark to death. According to Charles Darwin in The Voyage Of the Beagle (1845), Darwin was told by a Doctor Allen of Forres, UK that the Diodon actually had been found "floating alive and distended, in the stomach of the shark" and had been known to chew its way out of shark bodies after being swallowed, causing the death of its attacker. 
- They may be poisonous, through the accumulation of tetrodotoxin or ciguatera.
There are currently five recognized extant species in this genus:
- Diodon eydouxii Brisout de Barneville, 1846 (Pelagic porcupinefish)
- Diodon holocanthus Linnaeus, 1758 (Long-spined porcupinefish)
- Diodon hystrix Linnaeus, 1758 (Spot-fin porcupinefish)
- Diodon liturosus G. Shaw, 1804 (Black-blotched porcupinefish)
- Diodon nicthemerus G. Cuvier, 1818 (Slender-spined porcupinefish)
Fossils of porcupinefishes are known from Tertiary-aged marine strata. These species are similar to modern species. Some species include:
- Diodon tenuispinus, from the Ypresian-aged Monte Bolca lagerstatte.
- Diodon scyllai, from middle Miocene-aged Piemonte, Italy.
Diodon holocanthus puffed up and taken out of the water.
- Sepkoski, Jack (2002). "A compendium of fossil marine animal genera". Bulletins of American Paleontology 364: p.560. Retrieved 2007-12-25.
- Lieske, E. and Myers, R.F. (2004) Coral reef guide; Red Sea London, HarperCollins ISBN 0-00-715986-2
- Darwin, Charles (1845). Journal of researches into the natural history and geology of the countries visited during the voyage of H.M.S. Beagle round the world, under the Command of Capt. Fitz Roy, R.N. 2d edition. London: John Murray. p. 14.
- Froese, Rainer, and Daniel Pauly, eds. (2012). Species of Diodon in FishBase. October 2012 version.