seatrench:

A Pufferfish inflating itself by rapidly intaking water

(source)

Friendly reminder not to provoke pufferfish into puffing, and NEVER to take one out of the water unless you intend to eat it. If they puff themselves up with air instead of water, they can end up not being able to blow it back out, rendering them helpless. Buckets are your friend with these guys. Really, with all fish, but especially with these guys.

That said, this is both interesting and adorable.