After some soul searching I have recently decided to expand my territory from weekly fishes to weekly water critters in general, for the seas, lakes and rivers of the world are filled with too many amazing animals to just limit myself to the scaly ones. And what better way to start than by presenting one of my favourite animals of all time, the little marine sea slug Glaucus atlanticus. Known by various wonderful names including sea swallow and blue dragon, this stunningly beautiful creature employs one of the most nifty acts of thievery in the animal kingdom.
This video shows a blue dragon attempting to nibble at its favourite prey, the Portugese man-o-war, a colonial creature consisting of lots of tiny jellyfish-like organisms. The man-o-war is known for its nasty sting of course, resulting from lots of tiny pressurised venom-filled cells that fire little harpoons into unsuspecting fishes and other potential prey. The blue dragon’s slug mucus, however, makes it completely immune to these stingers, allowing it to safely eat away at the man-o-war. Moreover, rather than digesting the stinging cells, the slug sequesters and incorporates them into the tips of its many finger-like tentacles, making the blue dragon a rather unexpectedly dangerous little animal. Indeed, by concentrating the venom in its fingers, the sting of the blue dragon actually packs more of a punch than that of the man-o-war.
The question is, of course, how did this odd ability evolve? As of yet, this is unknown, though marine biologist Jessica Goodheart is currently working on this very problem. Even though my fondness of fishes should never be questioned, I do feel the urge to dust off an old adage of mine: sea slugs are awesome. Don’t ever forget it.