Blue-Ringed Octopus

One half of a deadly duo, the blue-ringed octopus enjoys an interesting symbiotic relationship with colonies of bacteria that inhabit its salivary glands. The bacteria produce potent neurotoxins that can kill a human in just a few minutes yet appear to have no harmful effect on the octopus. This toxic saliva, injected through shells broken with the octopus’s birdlike beak, also helps it to digest crabs and mollusks — via National Geographic