Diodon

This article is about the fish. For the clipboard software, see Diodon (software).

Porcupinefishes or balloonfishes, are any of the various species of the genus Diodon, the type genus of Diodontidae.

Porcupinefishes Temporal range: 55–0 Ma PreꞒ Ꞓ O S D C P T J K Pg N Early Eocene to Present[1]
Diodon holocanthus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Tetraodontiformes
Family:	Diodontidae
Genus:	Diodon Linnaeus, 1758
Type species
Diodon hystrix Linnaeus, 1758

Distinguishing features

Fish of the genus Diodon have:

• two-rooted, movable spines (which are derived from modified scales) distributed over their bodies.
• beak-like jaws, used to crush their hard-shelled prey (crustaceans and molluscs).^[2]

They differ from the swelltoads and burrfishes (genera Cyclichthys and Chilomycterus, respectively), which, in contrast, have fixed, rigid spines.

Defense mechanisms

• 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.^[3]
• They may be poisonous, through the accumulation of tetrodotoxin or ciguatera.^[2]

Species

Fossil dental plate of Diodon. Miocene of United States

Extant

There are currently five recognized extant species in this genus:^[4]

Image	Scientific name	Common Name	Distribution
	Diodon eydouxii Brisout de Barneville, 1846	Pelagic porcupinefish	circumtropical distribution
	Diodon holocanthus Linnaeus, 1758	Long-spined porcupinefish	tropical zones of major seas and oceans
	Diodon hystrix Linnaeus, 1758 ()	Spot-fin porcupinefish	tropical and subtropical waters of the world, including the Mediterranean Sea
	Diodon liturosus G. Shaw, 1804	Black-blotched porcupinefish	tropical and subtropical waters of the Indo-Pacific area from eastern coasts of Africa to Japan
	Diodon nicthemerus G. Cuvier, 1818	Slender-spined porcupinefish	southern Australia, as far north as Port Jackson to Geraldton, Western Australia

Fossil

Fossils of porcupinefishes are known from Tertiary-aged marine strata. These species are similar to modern species. Fossil species include:

• Diodon tenuispinus, from the Ypresian-aged Monte Bolca lagerstatte.
• Diodon scyllai, from middle Miocene-aged Piemonte, Italy.

References

1. Sepkoski, J. (2002). "A compendium of fossil marine animal genera". Bulletins of American Paleontology. 364: 560. Archived from the original on 2011-07-23.
2. Lieske, E. & Myers, R.F. (2004): Coral reef guide; Red Sea London, HarperCollins ISBN 0-00-715986-2
3. Darwin, C. (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.
4. Matsuura, K (2014). "Taxonomy and systematics of tetraodontiform fishes: a review focusing primarily on progress in the period from 1980 to 2014". Ichthyological Research. 62 (1): 72–113. doi:10.1007/s10228-014-0444-5.