Members of the diodontidae, species of the genus diodon are usually known as porcupinefishes or balloonfishes.

Distinguishing features

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).^[2]

They differ from the swelltoads and burrfishes (genus Cyclichthys and Chilomycterus), which have fixed, rigid spines.

Defense mechanisms

• Like pufferfishes they can inflate themselves, making their spines stand perpendicular to the skin. When inflated they pose a major difficulty to their predators: a large diodon fully inflated 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 was known to chew its way out of shark bodies after being swallowed, causing the death of its attacker and it known to have happened in several instances.
• They may be poisonous, through the accumulation of tetrodotoxin or ciguatera.^[2]

Species

• Pelagic porcupinefish, Diodon eydouxii (Brisout de Barneville, 1846)
• Long-spine porcupinefish, Diodon holocanthus (Linnaeus, 1758)
• Spot-fin porcupinefish, Diodon hystrix (Linnaeus, 1758)
• Black-blotched porcupinefish, Diodon liturosus (Shaw, 1804)
• Slender-spined porcupine fish, Diodon nicthemerus (Cuvier, 1818)

• 

  Diodon holocanthus

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  Diodon hystrix

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  Diodon liturosus

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  Diodon nicthemerus

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  Diodon holocanthus puffed up and taken out of the water.

References

1. ^ Sepkoski, Jack (2002). "A compendium of fossil marine animal genera". Bulletins of American Paleontology 364: p.560. http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=611&rank=class. Retrieved 2007-12-25. 
2. ^ ^{a b} Lieske, E. and Myers, R.F. (2004) Coral reef guide; Red Sea London, HarperCollins ISBN 0-00-715986-2