Diodon

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

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).^[1]

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

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.^[2]
They may be poisonous, through the accumulation of tetrodotoxin or ciguatera.^[1]

Fossil dental plate of Diodon. Miocene of United States

There are currently five recognized extant species in this genus:^[3]

Image	Scientific name	Common Name	Distribution
File:Diodon eydouxii Muroto1.jpg	Diodon eydouxii Brisout de Barneville, 1846	Pelagic porcupinefish	circumtropical distribution
File:Pez erizo de espinas largas (Diodon holocanthus), Cabo San Lucas, Baja California, México, 2024-12-18, DD 98.jpg	Diodon holocanthus Linnaeus, 1758	Long-spined porcupinefish	tropical zones of major seas and oceans
File:Pez erizo moteado (Diodon hystrix), islas Ad Dimaniyat, Omán, 2024-08-13, DD 108.jpg	Diodon hystrix Linnaeus, 1758 ()	Spot-fin porcupinefish	tropical and subtropical waters of the world, including the Mediterranean Sea
File:Pez erizo de manchas negras (Diodon liturosus), Zanzíbar, Tanzania, 2024-06-01, DD 90.jpg	Diodon liturosus G. Shaw, 1804	Black-blotched porcupinefish	tropical and subtropical waters of the Indo-Pacific area from eastern coasts of Africa to Japan
File:Globe Fish (Diodon nicthemerus) (49946933118).jpg	Diodon nicthemerus G. Cuvier, 1818	Slender-spined porcupinefish	southern Australia, as far north as Port Jackson to Geraldton, Western Australia

Fossils of Diodon are known from Tertiary-aged marine strata. These species are similar to modern species. Fossil species include:^[4]

↑ ^a ^b Lieske, E. & Myers, R.F. (2004): Coral reef guide; Red Sea London, HarperCollins Template:ISBN
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