7. Blue Ringed Octopus
The blue-ringed octopus is a species of poisonous octopus with four sub-groups that are found all over the Pacific and Indian Ocean. The tiny octopuses range from five to eight inches but pack a powerful poisonous punch and are recognized as the most poisonous marine animals on earth. Do not handle these creatures or they will become aggressive and agitated and can kill an adult human in minutes.