Blue ring octopus. According to the query related information, the blue ring octopus is one of the most dangerous animals on the seabed, the blue ring octopus toxicity is very strong, the cannonball fish is not so dangerous compared to it. Blue ring octopus, belonging to the octopus family, commonly known as the blue ring octopus, leopard octopus is widely distributed in the Pacific Ocean between Japan and Australia, is a very small octopus species, arm spanning no more than 15 centimeters.