Inflated pufferfish (Diodon holocanthus). The pufferfish, or porcupinefish, inflates itself when threatened by gulping in water. This dramatically increases its size, and causes the spines on its skin, which usually lie flat, to stick out. This appearance deters predators. This pufferfish inhabits tropical coastal waters in the Atlantic, including the Caribbean Sea, and Pacific Oceans. It is mainly nocturnal, emerging at night to hunt crabs, shellfish and sea urchins, which it breaks up with its powerful beak-like mouth. It may reach a length of up to 50 centimetres.