Common Octopus (Octopus vulgaris): You'll be lucky if you see an octopus while snorkelling the Reef Crest. Not because it's rare but because of its extraordinary ability to hide in plain sight. Using a network of pigment cells and specialized muscles in the skin, the Common Octopus can almost instantaneously match the colours, patterns, and even textures of its surroundings. Predators such as sharks, eels, and dolphins plus eager snorkellers swim by without even noticing it. Massive bulbous head, large eyes, and eight distinctive arms give it a unique appearance. Under threat it will release a cloud of black ink that both obscures its attacker's view and dulls a predator's sense of smell, making the fleeing octopus harder to track. Their soft bodies can squeeze into impossibly small cracks and crevices where predators can't follow and if all else fails, an octopus can lose an arm to escape a predator's grasp and regrow it later with no permanent damage. Watch out for the beak-like jaw that can deliver a nasty bite and the venomous saliva used mainly for subduing prey. The Common Octopus can grow to about 4.3 feet in length and weigh up to 22 pounds although averages are much smaller. They prey on crabs, crayfish, and molluscs, and will sometimes use their ink to disorient their victims before attacking.