As one of my good friends in Lansing likes to say, “Nature is a mother.” Never more is this true than in the constant arms race being waged between species either trying to eat or escape being eaten. One common strategy for self-defense is the evolution of natural toxins, both poisons that course through the veins or seep off of sharp surfaces and venoms that are actively injected into one’s opponent.
Perhaps even more interesting than the evolution of such toxins is the ability to coopt another creature’s defense mechanism. For example, the African crested rat neither produces poison nor does it eat venomous animals. Instead, it chews up toxic tree bark and slathers itself with the remnants. Or there’s the Spanish shawl – a deep-water sea slug so named for the orange fringes hanging off of its sides – that has a much more sinister approach. These guys eat and digest the bodies of tiny predatory worm-like animals. That is, all of them except their developing stinger cells, which it instead transports to its own outgrowths where they mature.
It’s sort of like eating a wasp and internally transporting its stinger to the tips of your own fingers – a real-life Gryffindor sword that takes in only that which makes it stronger.
The newly coopted defense stinger can come in quite handy for the Spanish shawl. For instance, it can use it to escape a much larger predatory sea slug such as Pleurobranchaea californica, as shown in this pretty awesome video (gotta love that victory dance).
Besides being wildly entertaining, however, this video was also the beginnings of an interesting discovery. The big, gross, white sea slug is basically a teenage boy; it will eat absolutely anything in its path. But if you watch the last little bit of that video, you’ll see something that no scientist had ever seen before – the hungry sea slug turned away from a potential meal.
If you saw me as a 14-year-old growing boy turn away from a Whopper plopped down right in front of me, you’d have called the scientific journals too.
As it turns out, this living garbage disposal is smarter than previously known. After coming into contact with something that it decides is most definitely not worth eating – such as a stinging Spanish shawl – it will not try to devour another one, even more than three days later. That is, of course, unless you starve it first.
Then Pleurobranchaea californica don’t give a shit, and it ravenously eats the Spanish shawl anyway.
This story, discovery, and research paper really doesn’t have much more to it. I just thought the Spanish shawl and the video were pretty cool. I’m not sure how to end this, so I give you a small bow.
The paper, “Selective prey avoidance learning in the predatory sea slug Pleurobranchaea californica,” was published in the Journal of Experimental Biology by University of Illinois molecular and integrative physiology professor Rhanor Gillette.