Porcupine fish | by Ocean Reality

Porucpine fish (Tetraodontiformes) go by the common names of blowfish, globefish, balloonfish, or pufferfish, because of their ability to expand their bodies by rapidly swallowing water (or air). This little trick keeps them from being eaten by predators, because they are then to big to be swallowed.

As an additional line of defense, some species produce a very powerful poison in their internal organs, making them a rather risky snack.