Species sort-of of the Week week #5 OR On the benefits of a tautonomical diet

Post previously published at Rah Rah Radula.

I'm sure you've heard the conspiracy theory that sea slugs are involved in a major trans-species arms smuggling operation. Well, your humble narrator has done some investigative journalism for which she is completely unqualified and can tell you, the rumors are true. That's why I'm cheating today, starting a Species species of the Week week with a nudibranch that's not even close to a tautonym (2). Here is the culprit:

Blue Dragon
Glaucus atlanticus(1)

Figure 1. Glaucus atlanticus - the Blue Dragon (nudibranch). Holy Daenerys Targaryen, Batman! Am I right?! This thing is crazy, and if your heart doesn't explode just a little bit when you see this and contemplate that you share the earth with this creature, well ... I can only sputter my disbelief.

Ok, so it looks cool, fine. But why does it deserve the [ahem, rather distinguished] honor of being a Species species of the Week week (weak?) when it's not even a tautonym (but see style="font-size: xx-small;">(2))?! Well, there was a passage in the Wikipedia entry:

G. atlanticus preys on other, larger pelagic organisms: the dangerously venomous Portuguese Man o' War Physalia physalis; the by-the-wind-sailor Velella velella; the blue button Porpita porpita; and the violet snail, Janthina janthina. Occasionally, individual Glaucus become cannibals given the opportunity.

Did you catch that? Almost every major prey item for this nudibranch is a tautonym (and Physalia physalis is just obnoxiously close - what a jerk)! Now I'm not saying that the diet of this slug is explained by the possession of a highly sophisticated taste - if I do say so myself - in grammar. For one, though I admittedly haven't done the research to back this up, I feel like it's safe to assume the emergence of the slug's diet predates the naming of these prey species. But still...what are the odds? Really, I'd love to know what the odds are if anyone is patient enough to figure that out.

In the next few tautonym posts (3), I'll cover a few of the double-named prey of the Blue Dragon - except definitely not that tease Physalia physalis.

But now back to the arms smuggling operation...

So, of course I'm all fixated on the improbability of an almost exclusively tautonomical diet, when I am reminded that what's even cooler, at least to most people, is that this diet is also the slug's defense. When the slug consumes jellies, it also eats the stinging cells (Figure 2). The slug then puts these cnidocytes into its own flesh (the cerata, specifically, which are the long finger-like projections that make this slug look so flamboyant). Anything that tries to attack the slug gets stung.

Figure 2. This is why it hurts, y'all. I know, my eyes just glaze over too when I see diagrams in the pastel color palette of academic textbooks (haven't they figured that out yet?). But this really is one of the better diagrams of how Cnidocytes work - terrifying.

So the slug has basically stolen poisoned harpoons from the jellies and incorporated them into it's own body so it becomes super-invulnerable. This, of course, reeks of Hollywood script possibilities (whoops, it appears I've been scooped. SPOILER ALERT: it doesn't end well for the invulnerable trans-species defense idea). Here is a National Geographic clip demonstrating the awesomeness of the Blue Dragon (4) There is, of course, a word for this process of stealing cnidocytes and deploying them against your enemies: Bioterrorism. No, well maybe, but the real word is Kleptocnidae.

Next up: Goodyear Mollusks.

References and miscellany (5):

(1) Pokemon disambiguation found here, in French.

(2) G. atlanticus was, however, the first (of only two) species named in the genus Glaucus, so according to my theory of tautonyms, it could have theoretically been Glaucus glaucus. And, frankly, if I'm going to editorialize here, atlanticus is a misleading species name (though hardly the only one) as the distribution of this species is not restricted to only the Atlantic ocean.

(3) Read: Until I get bored.

(4) Editorial aside: Why does everyone now have these narrators that are so over the top for nature videos?! This guy sounds so incredulous and has the dumbest comments. This is why I like David Attenborough and Marty Stouffer. They get it: nature sells itself and doesn't need a monster truck voice-over to make it exciting. That's another soapbox for another day though.

(5) Does Blogger have a reference management software? Rearranging these is getting rul old.

Emily Grason


  1. Anyone rushed enough to skip over the references and miscellany is really missing out here!...:)
    RH or Your cousin Randi Hilary


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