If you have heard of sushi, you have probably heard of fugu. (Or perhaps you saw this and wondered what exactly fugu was.) The dish is made from some parts of the tiger pufferfish (so called because they puff themselves into balls), Takifugu rubipes, and has become a notorious example of Japanese culture. Small wonder; the Japanese have been consuming the flesh of pufferfish for years, leading to some adorable marketing as well as culinary notoriety.
Why is this dish so well-known? Because sashimi made from this pufferfish kills people every year. Fugu contains tetrodotoxin, a poison 1200 times deadlier than cyanide. This poison is also found in a few other venomous creatures, such as cone snails and the blue-ringed octopus. (I was going to do the octopus today, but thought that fugu would amuse you all more. Plus, I had sushi for lunch. XP)
Fugu chefs have to be trained for seven years. One wrong cut could kill; a little bit of poison produces a light tingling sensation, but an overdose (from, say, cutting into the highly toxic liver or ovaries of a tiger puffer) can kill a person withing 24 hours. Since it is so poisonous, the Emperor of Japan is forbidden from eating fugu. This deadly dish is often presented in the shape of a chrysanthemum, a flower associated with funerals in Japan, or at least served on a chrysanthemum plate.
How to cut your still-living puffer fish.
The fish is, interestingly enough, not to blame for its toxicity. It is poisonous for the same reason that monarch butterflies are poisonous: They eat something else toxic. In this case, it's a certain kind of Pseudomonas bacterium, which is found on other toxic critters. Captive-bred tiger puffers do not exhibit any toxicity until they are fed poisonous food. Regardless of how it gets there, the result is pretty damn lethal.
Oh, Japan, you so craaazy!
(On another note, puffer fish and one of my favorite groups of fish in the sea, triggerfish, are related. Indonesia is sucking me in with its awesome fauna slowly but surely.)