Here on io9, we love our poo-rolling friends. And rightly so! They provide a crucial ecological service. They have surprising capacity to navigate the world. They're amazingly strong. They're often comical in their persistence. They horrify our less rational friends. They look cute in little booties, and some of them are positively gorgeous. They're one of nature's greatest gifts to us.
At the very least, they're harmless, right? Most dung beetles get all the nutrients they need, birth to death . . . yep, from dung. Their eggs hatch in darkness, surrounded by poo . . and they must eat their way to freedom (making them among the best AND worst parents ever!). Even at their worst, they get rid of stuff that most of us would rather not be bothered with.
I could go on, but I shall defer to a far better source to round out their virtues.
(Cue Ze Frank)
So, what happens when one of our little friends decides to get ambitious?
I'm here to tell you about the dung beetles that gave up dung. I bring you . . .
The Murder Beetles.
As a strange side effect of their descent into the bowels of coprophagy, our scarab friends have evolved into surprisingly tough little monsters. They're able to to handle a number of surprisingly harsh environmental conditions and have the external and internal defenses to match. Also, they are disconcertingly hard to squish. Animals that would be parasites to us just take a 'hope for the best' strategy with them.
So they can take it, but can they dish it out? They can't have needed to evolve much in the way of fighting techniques when their prey item is an amorphous solid, can they? What would one do if a big old millipede said something really bad about its mom?
No, my first guess wasn't 'murder it with zeal, take it home, and chop it up' either .
Of course, we don't know that this particular millipede said anything of the sort. Our science just isn't that good (yet!). What we do know is that this particular dung-free beetle, deltochilum vagalum, does this to millipedes quite a lot . . . so while there is still a distant chance that this is all a dreadful misunderstanding it seems much more likely that our harmless little friends have developed a taste for this sort of thing.
Tragically for those still dreaming of a future where these guys got along, actual science™ is on the side of the-creatures-formerly-known-as-dung-beetles becoming... murder beetles.
They've been evolving to do this for a very long time, and while their adaptations are only impressive when compared to other dung beetles (having a slightly modified head and 'special dragging leg' doesn't exactly turn a dung beetle into an offensive terror when compared to . . . actual weapons), that clearly doesn't matter to this little guy. Their favored enemy is 'things that stop moving when you pry them apart'. That's a big list.
One could fairly point out that millipedes, while tough to kill, don't exactly inspire fear in the undergrowth. Nothing hears the tiny pitter patter of their many feet and is inspired to flee (okay, almost nothing). Even plants, so frequently residing on the bottom of the food web, are far too annoyingly living for a millipede to put his squeamish little mandibles on.
So, how would dung/murder beetles fare against prey that might actually try to murder them back?
Aha... Pretty good then.
The one on bottom is a leafcutter ant queen, and while they may be farmers . . . they will completely ruin your day if you try to screw with them. They fear parasitoid phorid flies, army ant swarms, mammals adapted to the point of near absurdity, and boredom.
The little one on top there is Canthon virens. . . and what's going on is not a loving embrace or a strange sort of phoresy. We know this because the ant queen usually ends up mostly decapitated in the next picture (Yes, mostly. . . it's as bad as it sounds). These guys hunt ant queens because . . . of course they do. Isn't that the next logical step up from a ball of dung?
I hope you're seeing a disturbing trend here, because I do, and I don't want to be alone.
Dung/murder beetles are the arthropod world's equivalent of badgerdillos.
These little guys punch way above their weight class, and their lot in life is literally crap. When they go postal on something they tend to commit murder. . . a lot. My suspicion is that they suddenly come to, in the middle of what has to be the tastiest stuff they've ever seen in their lives. . .and from there the rest is inevitable.
The only reason that us and every other animal in the world exists is because dung beetles only know how to eat one thing at a time. We've just got to keep doing what everybody else is doing and hope they never notice that we're made of food.
If they do . . .
(note: My theory has not been investigated by Actual Science™)