When aggravated by a predator, they, you know, puff up. Some puffers ... Contrary to what it looks like, puffer fish are not like balloons. Because what's normally inside them isn't air.

Not every fish has scales. Shocking, right? Puffer fish have smooth skin covered in spines. The spines lay flat until they puff up, so they're not easy to see most of the time. Their smooth skin ...