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

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

s). They differ from the

swelltoad ''Cyclicthys'' is a genus of fish in the porcupinefish family, Diodontidae. Species in the genus are often known as swelltoads. Distinguishing features Fish of the genus ''Cyclicthys'' have three-rooted, rigid spines (actually modified scales) ...

s and

burrfishes ''Chilomycterus'' is a genus of diodontid tetraodontiform fishes commonly called "burrfish." Species There are currently 5 recognized species in this genus:Matsuura, K. (2014): Taxonomy and systematics of tetraodontiform fishes: a review focusi ...

(genera ''

Cyclichthys ''Cyclicthys'' is a genus of fish in the porcupinefish family, Diodontidae. Species in the genus are often known as swelltoads. Distinguishing features Fish of the genus ''Cyclicthys'' have three-rooted, rigid spines (actually modified scales) ...

'' and ''

Chilomycterus ''Chilomycterus'' is a genus of diodontid tetraodontiform fishes commonly called "burrfish." Species There are currently 5 recognized species in this genus:Matsuura, K. (2014): Taxonomy and systematics of tetraodontiform fishes: a review focusi ...

'', respectively), which, in contrast, have fixed, rigid spines.

Defense mechanisms

* Like true

pufferfishes Tetraodontidae is a family of primarily marine and estuarine fish of the order Tetraodontiformes. The family includes many familiar species variously called pufferfish, puffers, balloonfish, blowfish, blowies, bubblefish, globefish, swellfish ...

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.Lieske, E. & Myers, R.F. (2004): ''Coral reef guide; Red Sea'' London, HarperCollins

Species

Extant

There are currently five recognized extant species in this genus:

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 Monte Bolca is a lagerstätte near Verona, Italy that was one of the first fossil sites with high quality preservation known to Europeans, and is still an important source of fossils from the Eocene. Geology Monte Bolca was uplifted from the T ...

lagerstatte. * '' Diodon scyllai'', from middle Miocene-aged Piemonte, Italy.

References

Diodontidae Extant Ypresian first appearances Marine fish genera Taxa named by Carl Linnaeus {{Tetraodontiformes-stub