The blue-ringed octopus is only about 20 centimeters when the arms are extended, and weighs only about 50 grams (Blue-ring 2004). Despite its small size, it is one of Australia's most deadly creatures because its saliva contains a neuromuscular poison which is extremely potent and causes immediate paralysis of the respiratory system, with death occurring with one and a half hours unless treatments is instituted rapidly. The octopus is found in all Australian states, and the two main species are the larger tropical species, Hapalochlaena irrnulata, and the common southern species, H. mactrlosa.
Like other octopuses, the blue- ring has many small suckers shaped liked cups on the arms which help it to pick up objects (Blue-ring, 2004). Its diet consists of crustaceans, particularly crabs, and molluscs. A larger species, the H. lunulata, which measures about 5" across the body, is found between the Philippines and Indonesia, as well as from Papua New Guinea to Vanuatu (Bluering, 2004). Here it inhabits the coral reefs and hunts for crustaceans and smaller molluscs.
The blue-ringed octopus has two large salivary glands (venom glands) situated above its brain (Blue-ring, 2004). A duct leads through the brain into the mouthparts which terminate in a small, parrot-like beak found at the junction of its eight arms. When hunting for crabs, the octopus swims over its prey and sprays its poisonous saliva into the sea around it. The crab absorbs the poison and becomes paralyzed within minutes, allowing the octopus to capture it and devour it. The octopus sometimes jumps on its prey, surrounds it with its eight tentacles, and bites it (Dangers, 2004). Poison from one of the glands is used on its main prey, crabs, and is relatively harmless to humans. Poison from the other gland serves as defense against predators and can be lethal to humans.
The habitat of the blue-ringed octopus is the rock pools around the Australian coa...