pufferfish

Short definition from Wiktionary

Noun

1. 1
   Any species of fish of the family Tetraodontidae that have the ability to inflate themselves to a globe several times their normal size by swallowing water or air when threatened; puffer, blowfish, swellfish, balloonfish, globefish.
2. 2
   The meat of these fish, a delicacy popular in Japan served raw as sushi that may, if improperly prepared, contain deadly levels of neurotoxins; (Japanese) fugu.