Porcupinefish

Porcupinefish are fish of the family Diodontidae (order Tetraodontiformes). Porcupinefish is also commonly called porcupine puffer (and, sometimes, "balloonfish").

The porcupinefish is closely related to the pufferfish, the main difference is that porcupinefish has spines on its body.

Porcupinefish has the ability to inflate its body by swallowing water (or air) and become round like a ball. This increase in size (almost double vertically) reduces the range of potential predators to those with much bigger mouths (but these prefer to spend their hunting energy on fish more substantial than the largely empty ball of porcupinefish.)

Worse yet: The sharp spines (of varying length among species), extending radially outwards, make it much more difficult to swallow and present an additional deterrent for would-be predators; this defense seems to be insurmountable for all but most determined eating machines, such as sharks and killer whales (juvenile porcupinefishes may also fall prey to tuna and dolphins.)

And if all this is not enough, some purcupinefishes also carry the extremely deadly poison tetrodotoxin in their skin and/or intestines, making them a rather unappetizing morsel.

Information sites

• FishBase - Genus "Diodon"
• FishBase - Species "Diodon holocanthus"
• Florida Museum of Natural History - Species "Diodon holocanthus"