Porcupinefish (Diodon nichthemerus) (commonly called blowfish or balloonfish) live in warm shallow waters around the world, usually on coral reefs. They are sometimes confused with pufferfish as they share the ability to inflate themselves but they are different, having many thicker, more prominent spines that are often extremely poisonous.

The fish’s defence reaction is very effective as it works in three ways. The fish can nearly double in size thus limiting the potential predators to those with mouths big enough to swallow it; there are the obvious spines to which it owes its name; the poison that the spines inflict can be deadly to humans as well as predators.

This specimen is a slender-spined porcupinefish from the waters around Australia.