Porcupinefish

Porcupinefish are medium-to-large fish belonging to the family Diodontidae from the order Tetraodontiformes which are also commonly called blowfish and, sometimes, balloonfish and globefish. The family includes about 18 species. They are sometimes collectively called pufferfish, not to be confused with the morphologically similar and closely related Tetraodontidae, which are more commonly given this name.

They are found in shallow, temperate, and tropical seas worldwide. A few species are found much further out from shore, wherein large schools of thousands of individuals can occur.

The following genera are known:

The following genera are known only from fossil remains:

Porcupinefish are generally slow-moving.

They have the ability to inflate their bodies by swallowing water or air, thereby becoming rounder. This increase in size (almost double vertically) reduces the range of potential predators to those with much larger mouths. A second defense mechanism is provided by the sharp spines, which radiate outwards when the fish is inflated.

They have upper and lower teeth that fuse into a shape of a parrot's beak; they use this beak to eat molluscs and sea urchins.

Some species are poisonous, having tetrodotoxin in their internal organs, such as the ovaries and liver. This neurotoxin is at least 1,200 times more potent than cyanide. The poison is produced by several types of bacteria obtained from the fish's diet. As a result of these three defenses, porcupinefish have few predators, though adults are sometimes preyed upon by sharks and orcas. Juveniles are also preyed on by Lysiosquillina maculata, tuna, and dolphins.