The Pufferfish is can inflate itself when attacked. Its skin and internal organs contains tetrodotoxin, which is 120 times more poisonous than cyanide.
In January 2014 was it documented by BBC that dolphins on purpose get intoxicated by playing with Pufferfish and gently passing it around to the other dolphins. The Pufferfish released poison from the skin into the water, and when the dolphins inhaled it, they started to behave in a peculiar way.
Pufferfish flesh is not poisonous and is considered a delicacy in Japan and Korea. It is prepared by specially trained chefs.