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 distributed over their bodies.
  • beak-like jaws, used to crush their hard-shelled prey.
They differ from the swelltoads and burrfishes, 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 erect spines stand perpendicular to the skin, so pose a major difficulty to their predators; a fully inflated, large porcupinefish can choke a shark to death. According to Charles Darwin in The Voyage Of the Beagle, 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.

    Species

Extant species

Currently, five extant species are recognized in this genus:
ImageScientific nameCommon nameDistribution
Diodon eydouxii Brisout de Barneville, 1846Pelagic porcupinefishcircumtropical distribution
Diodon holocanthus Linnaeus, 1758Long-spined porcupinefishtropical zones of major seas and oceans
Diodon hystrix Linnaeus, 1758Spot-fin porcupinefishtropical and subtropical waters of the world, including the Mediterranean Sea
Diodon liturosus G. Shaw, 1804Black-blotched porcupinefishtropical and subtropical waters of the Indo-Pacific area from eastern coasts of Africa to Japan
Diodon nicthemerus G. Cuvier, 1818Slender-spined porcupinefishsouthern Australia, as far north as Port Jackson to Geraldton, Western Australia

Fossil species

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