3. Blood Disorders. Blood disorders such as hemophilia and leukemia can cause unexplained bruising, often because your blood fails to clot properly. If you have severe and frequent unexplained bruising, it's a good idea to see a physician to rule out such disorders, especially if it seemed to come on suddenly.
Puffer fish contain the potent neurotoxin tetrodotoxin. TTX is thought to be synthesized by a bacterial or dinoflagellate species associated with the puffer fish. The toxin is concentrated in the liver, gonads, and skin. The level of toxicity is seasonal, and, in Japan, fugu is served only from October through March.
The chef doesn't learn how to remove the tetrodotoxin. He learns which parts of the fish contain it, how to avoid those parts, and how to avoid contaminating the non-toxin-bearing flesh with the toxin. Tetrodotoxin cannot be removed without using chemicals that would make the fish inedible.