20. The Electric Eel
Human beings are electrical conductors to some degree, as anyone who has played with a plasma globe knows well. But the electric eel is a whole different beast. It can unleash its own lightning storm at will, like some kind of oceanic Thor. The eel (which is actually not an eel, but a member of the much more badass-sounding "knifefish" family) is a living, breathing stun gun that can knock its prey out cold, simplifying the hunting process immensely. It's no surprise that with such a shocking adaptation, it's the apex predator of its environment.