Blue-ringed Octopus

The blue-ringed octopus is a small octopus found in tide pools and coral reefs across the Indian and Pacific Oceans, unusual among octopuses for carrying venom potent enough to be lethal to humans, despite a body typically no larger than a golf ball. When threatened, it displays a striking warning pattern of iridescent blue rings across its skin, a signal that it can otherwise conceal by adjusting its coloration for camouflage against the seafloor. Its venom, produced with the help of bacteria and containing the neurotoxin tetrodotoxin, the same compound found in pufferfish, can cause paralysis and respiratory failure in a human bite victim, and because the bite itself is often nearly painless, envenomation can go unnoticed until serious symptoms begin. Despite its danger to humans, the blue-ringed octopus is a small, shy and non-aggressive animal that generally bites only when handled or accidentally trapped, using its venom primarily to subdue small crabs and shrimp, its main natural prey.