Blue Ringed Octopus

The blue-ringed octopuses  are three octopus species that live in tide pools in the Pacific Ocean, from Japan to Australia. Despite their small size and relatively docile nature, they are currently recognized as one of the world's most venomous animals. They can be recognized by their characteristic blue and black rings and yellowish skin. They hunt small crabs, hermit crabs, and shrimp,and may bite attackers, including humans, if provoked.The blue-ringed octopus is 12 to 20 cm, but its venom is powerful enough to kill humans. There is no blue-ringed octopus antivenom available.The octopus produces venom that contains tetrodotoxin, 5-hydroxytryptamine, hyaluronidase, tyramine, histamine, tryptamine, octopamine, taurine, acetylcholine, and dopamine. The major neurotoxin component of blue-ringed octopus venom was originally known as maculotoxin but was later found to be identical to tetrodotoxin, a neurotoxin which is also found in pufferfish and cone snails. Tetrodotoxin blocks sodium channels, causing motor paralysis and respiratory arrest within minutes of exposure, leading to cardiac arrest due to a lack of oxygen. The toxin is created by bacteria in the salivary glands of the octopus.