Blue-Ringed Octopus
The blue-ringed octopus is native to Australia and is considered one of the most dangerous creatures in the ocean. Its saliva contains a type of neurotoxin that causes paralysis and respiratory failure. Also, their venom can paralyze as many as 10 humans. That’s a pretty powerful toxin for creatures that are only about 8 inches or 20 cm in size. But for the most part they are very docile unless they deem something a threat. Then they become quite dangerous.