Tremoctopus is a genus of pelagiccephalopods, containing four species that occupy surface to mid-waters in subtropical and tropical oceans. These magnificent sea creatures have cape-like webs that extend down their longest arms. The ‘blanket’, which can be rolled when not in use, makes them appear much bigger, helping them fend off predators. But these octopuses have an even more amazing defence strategy. They are immune to the sting of the deadly Portuguese man-o-wars, which means they can collect the jellyfish-like creature poisonous tentacles and use them as weapons against would-be attackers.