Glaucus atlanticus: The Blue Dragon


Glaucus atlanticus is known as the blue dragon and the blue sea slug. Pause a moment and say that name to yourself again, Glaucus atlanticus, oh the sounds of those syllables together gives me shivers! What beautiful coloring on this rare sea creature too!

So what is this blue dragon exactly? It’s a shell-less gastropod mollusk. How does it get around? It’s pelagic, meaning it floats upside down (because of the location of the gas filled sac in its stomach) at the surface tension of the water and is carried along by wind and ocean currents. It can also use its cerata (those finger like apendages) to swim around. You can find them in temperate and tropical waters such as off the coasts of Australia, South Africa, India, Peru, and Mozambique. The blue dragon is varying shades of blue on its ventral side (first image pictured) which acts as camouflage to predators from above yet is a silvery grey dorsally to hid it from predators below. It’s a 1.2in cutie that started garnering a lot of attention in April 2012 as a result of the image that appeared on Imigur (also pictured below).

be careful!
be careful –  don’t handle them like this!

Now, despite it’s cute appearance and small size the blue dragon is actually an aggressive predator that you should avoid skin contact with, unlike in the picture above. You see, a primary prey of Glaucus atlanticus is the Portuguese man o’ war (which is a collective colony of individual organisms, not a stinging jellyfish). This tiny sea slug absorbs the man o’ war venom and stores it in the tips of the dark cerata around its body. Keep in mind that the man o’ war is much larger than our cute sea monster (poison tentacles can range anywhere from 3.5in to 160ft depending on polyp type) and the absorbed poison is much more lethal at a higher concentration. If you simply must get a closer look or help a stranded blue dragon please follow the example of the following video.

Once the poison is stored, Glaucus atlanticus uses it as both an additional protection against predation and to prey on by-the-wind sailor (aka Velella velella), the blue button (aka Porpita porpita), and the violet snail (Janthina janthina). True to form this little sea slug has a radula full of serrated teeth which can be protruded to help devour it’s prey probably by rasping the particles of flesh from the surface.

blue dragon and a blue button

Well? What do you think of our cute yet deadly sea monster? Personally, I hope one day I’ll get to see you in person cutie patootie!

blue dragon and a by-the-wind sailor
blue dragon and a by-the-wind sailor

Sources; for more information:

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