Maximum length about 35 cm. The puffers are essentially warm-water species, but this one is found as far north as New York and even the south of Newfoundland. It has no counterpart in European waters.
Puffers have two unusual protective devices. They can inflate their abdomens to a remarkable extent, thus making themselves too much of a mouthful for predators. Moreover, their scales have been modified into small prickles which stand out when the abdomen is inflated, so that the prospective mouthful is not only too big but also too prickly.