puffer

or blowfish

Any of about 90 species (family Tetraodontidae) of fishes that, when disturbed, inflate themselves into a globular shape with air or water. Most species occur in warm and temperate seas worldwide; some occur in brackish or fresh water. Puffers have tough, usually prickly, skin; their fused teeth form a beaklike structure, split in the center of each jaw. The largest grow to 3 ft (90 cm) long, but most are considerably smaller. Though they contain a lethal toxin, they are sometimes eaten, especially in Japan, where puffers (called fugu) are prepared by a specially trained chef.

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See Tetraodontidae