Friends"¦with benefits
The ability to make new friends when your old ones disappear

Step 1: Pick the Right Crowd
The tiger keelback snake is native to Japan and several other nearby islands, where it's known for defending itself by spraying a toxin called bufadienolides into the eyes of its attackers. The toxins prevent proper heart function and give the snake a great getaway plan, but for years, scientists suspected that the tiger keelback wasn't capable of producing bufadienolides inside its own body. The chemical mystery was solved in 2007 when scientists started to take notice of the snakes' roommates. According to a January 2007 article in Cosmos magazine, almost all the islands where tiger keelbacks live are also home to several species of bufadienolides-secreting toads.

Step 2: Invite Your New Friends To Dinner
That discovery, of course, still left scientists with the question of how the toxins were getting from the toads' skin into the snakes. Assuming that there probably wasn't a bunch of teenage, hippy keelbacks slithering around licking the toads, researchers figured the toxin was getting transferred when the snakes ate their amphibious neighbors. It's a plausible solution, but an odd one. There are plenty of other animals that reuse the venom of another species, but those are almost exclusively invertebrates. It's not very often that you find backbone-blessed animals engaging in this sort of thing. But, researchers studied the spit of snakes from toad-ed and toad-free islands and found that, amazingly, they were right. In environments where no toads could be found, the snakes completely lacked the bufadienolides toxin.

Poisonous toad: It's what's for dinner.