It uses its powerful beak to easily break open the shells and exoskeletons of its prey. At night, it often rests on the peaks of sponges and coral. All pufferfish contain a toxin (tetrodotoxin) in their skin, their viscera and their reproductive glands. It comes from bacteria in their food.
In addition to their toxicity, pufferfish have another defence mechanism. To scare off predators, they swallow water, filling up their stomach, which stretches significantly, as does their skin. Once they are puffed up, they look much more intimidating and would be hard for a predator to swallow.