Some mothers cuddle their children every night. But for pufferfish, love means abandoning your larval babies soon after birth-- but only after slathering them with a good solid coat of deadly toxins. Females store toxin in the same location that they store eggs, so when one lays her eggs, she also releases toxin. At hatching time, the babies pick up some of the deadly poison on their way out. Predators apparently don't like the taste of the toxin, so they spit the babies back out after trying to eat them.
The toxin in question is tetrodotoxin, which is one of the deadliest poisons on earth. Mind-bogglingly, the pufferfish that produce this toxin are considered a culinary delicacy; diners "often want to taste just the tiniest tingle in their mouths from the poison to remind them how adventurous their meal is," but hundreds have been killed and poisoned from slightly incorrect preparations.
Perhaps even stranger, tetrodoxin is a crucial ingredient in the controversial but widely reported, much-studied, real-world practice of "voodoo zombification" in Haiti. Sorcerers (practitioners of the Vudun religion) reportedly mix toxins from cane toads, tree frogs, and pufferfish to cause in victims "a significant reduction in heart rate and metabolic activity," putting them into "a state in which they are completely paralysed but fully conscious." The victim, in a deep coma, is presumed dead and buried; the sorcerer disinters the body, revives the victim, and administers a second cocktail of plant-based drugs that induce delirium and disorientation. Supposedly, the victims are then put to work on sugar cane plantations, but occasionally wander back to their hometowns ("back from the dead") in a delirious, disoriented, bruised state-- giving rise to the legend of zombies.
Read medical research on zombification, published in the Lancet, here: http://www.researchgate.net/publication/13083933_Clinical_findings_in_three_cases_of_zombification
Check out this book for more on voodoo zombification and the origins of other "monsters": http://www.amazon.co.uk/The-Science-Monsters-Matt-Kaplan/dp/1472101154
In a paper published this month in Toxicon, researchers showed that larval pufferfish have more tetrodotoxin than they should. But it's not coming from the inside out; it's spread all over the surface of their skin. It turns out that extra tetrodotoxin is stored where female pufferfish keep their eggs. When she lays them, she also releases some of the toxin -- and it sticks to the babies once they hatch.