Pupa in Trinidad mimics snake (and moves!)

May 21, 2015 • 12:15 pm

This piece, from nerdist. com, describes one of the more amazing cases of mimicry I’ve seen. Look at the picture below, and see what you think it is:


It’s not a snake, despite the very snake-y appearance of the thing. It has eyes (fake), the eyes even have a “glint” in them (fake), it has a fake mouth, and even fake “scales”.

It’s from Trinidad, and it’s one of the life stages of a lepidopteran. In fact, it’s the pupal case of the Daring-Owl butterfly Dynastor darius darius, a subspecies from Trinidad (the species D. darius is found in Central and South America).

Here’s a picture of an adult of another subspecies, D. darius stygianus:

Dynastor_darius_062705_COSTA_RICA_HEREDIA_PROV._La_Selva_Biological_Station_Sarapiqui_27-VI-2005_Yahaira_Rojas_Duran_3And the caterpillar of D. darius darius, which is weird looking but not nearly as weird as the pupa:


It’s when this caterpillar becomes a pupa that it turns into a snake mimic, and the mimicry, as you can see above, is amazing. Here are a few more photos:



This is what the predator would see. Look at those eyes!


Now remember that the pupa is stuck in one place, which raises the question of why it mimics a snake. After all, a potential predator (likely a bird) inspecting the pupa might discover that it can’t move, and then nom it. But, as the article notes, the selective advantage of mimicking a snake doesn’t require movement or the ability to escape a predator once you’ve been spotted. The predator, seeing what looks like a snake, could simply flee without closer inspection.

But there’s more, for the pupa apparently can move—violently—when disturbed. A 1978 paper in Psyche by Annette Aiello and Bob Silberglied reports this in a few tantalizing words:

Screen Shot 2015-05-21 at 8.33.36 AM

I’d really like more information on how a pupa can “wave violently back and forth”, how it detects the predator, and what the movement is like. I believe the authors’ claim, for I knew both of them at Harvard, and they were scrupulous researchers (tragically, Bob was one of the victims of the 1980 crash of an Air Florida plane in Washington, D. C.). A mimetic and moving pupa like this is a remarkable product of natural selection.
There’s one more issue: the nerdist article notes this:
For 13 days, D. darius destroys and reforms itself inside what looks like the head of a Gaboon pit viper (though the snakes aren’t native to Trinidad).
And indeed, it does look like a Gaboon pit viper (Bitis gabonica):
The problem is that this snake is found only in west central Africa, and it’s unlikely that the pupa, found in the Americas, is mimicking it. For such mimicy to work, a potential predator must have had some kind of experience (either direct or through genes inherited from its ancestors) with the viper, which can’t be true in this case. The prediction, then, is that there must be some venomous snake in the range of D. darius that looks like the pupa, endowing a selective advantage to mimicry.  I’m not a herpetologist, but I know some of you out there will be able to pinpoint the potential “model.”
Credits: Pictures of Dynastor darius pupae from Andreas Kay; that of the Dyanstor daruis caterpillar from deviantArt//LuciRamms

h/t: Audrey

41 thoughts on “Pupa in Trinidad mimics snake (and moves!)

  1. It “looks like a Gaboon Adder” because that species has attributes, like a dark postorbital stripe, head scales, and so forth that are common to many vipers–of which there are plenty in Central and South American, including Trinidad. It IS an impressive case of mimicry, and the models are surely several species of neotropical pitvipers.

    1. Harry Greene is one of America’s most accomplished herpetologists. Check out his webpage at Cornell University.

  2. Ha! Was going to say the same thing – about Bothrops and Lachesis in Trinidad, but if Harry Greene already said it, no need to reiterate. 🙂 Lots of pupae do violently thrash around though. I do not know how they do it, but I once kept a sphinx moth pupae and when touched it would thrash around and had a pointy part on one end that was quite sharp and both that and the movement were rather startling.

    1. Wow, this is really incredible.

      As pointed out above, I’ve also experienced pupae thrashing about. I remember picking up a cabbage-butterfly pupa as a kid, and the sudden squirming freaked me out and I dropped it; natural selection did its job. The pupae I’ve seen “thrash” have a segmented “abdomen” like the one here. Chrysalises (don’t know pl.) like the Monarch’s don’t have segments and from my memory don’t move. I have no idea the implications of a segmented pupa or if there is a direct correlation between the segments and movement.

      Also, the fact that this snake-mimicking pupa doesn’t move doesn’t necessarily mean it’s not being “snake-like”. Snakes can stay motionless for long periods of time.

  3. Fantastic! I would need a change of underoos if I chanced upon such a pupae. Even knowing what it actually is, there’s a part of my brain that still freaks out a bit and dumps the adrenaline anyway, same as when encountering a Pantherophis obsoletus who curls up in some leaves and does a nice rattlesnake mimicry with its tail. The logical part of the brain says “oh, cool, a black rat snack, we should try to catch it” and the primitive part of the brain screams out “AHHHH! RUN! WE’RE GONNA DIE!!”

  4. In case it’s not obvious, a couple of those pictures are stereo pairs. Cross your eyes and merge the images to get the full 3D effect.

  5. Does it have to mimic a particular species? I looked an saw a “snake” not a “pit viper” or “anaconda” or whatever. My generic response to snakes is to avoid them unless I’m sure that they are harmless. It might be that looking like a generic snake would send enough potential predators in another direction to provide a survival advantage. Having achieved that there is always the option for selection to fine tune the look.

  6. That is worthy of the word “amazing”. I have never seen this kind of mimicry before. Thanks for sharing!

  7. What hath evolution wrought?!

    If I saw these in the wild, I’m not sure what I’d do, freeze or move. But I would be convinced that I was looking at a poisonous snake much too closely.

    It reminded me of a quote often attributed to Haldane/Eddington: The universe is not only stranger than we imagine, it is stranger than we can imagine.

    These are simply remarkable.

  8. One of the comments over the nerdist.com:

    I’m no creationist but how the hell does a catipilar evolve to mimic another animal?

    Sheesh. Are people’s imagination that paltry?! Or hell, just ability to read books! How else could this happen, except through mutation and selection?

    1. That’s a bit harsh. It’s quite likely that the language we use interferes with understanding, for those who lack sufficient previous exposure to the concepts. People read “mimic” and think “copy” (an intentional act) rather than “just happens to appear outwardly similar”. Comprehension can’t follow, unless and until they overcome that initial semantic misdirection.

  9. Many butterfly species have pupae that can wiggle back and forth when disturbed. Some squeak when doing so. A moving branch or passing shadow could provoke a response and enhance the warning value. Oh, oh, so much to know, and so little information.
    Many tree-climbing snakes, not just venomous species, prey on birds. Tropical birds are probably under immense selection pressure to respond suspiciously to anything even remotely resembling a snake. One bird-brained mistake, and that’s the end.
    Since Trinidad was connected to the South American continent as little as 12,000 years ago, Trinidadian Dynastor darius must have quite recently shared genes with populations from all over northern Venezuela. Even if the mimicry in pupae is directed to some specific snake, that snake is not necessarily a current resident of Trinidad.
    I add a link to another lepidopteran engaging in snake mimicry:

  10. I going to take a stab at how this pupae could mimic a West African species of snake. Plate tectonics. Both South America and Africa were part Gondwanaland and both may have been closer geographically at some stage after their split from the great southern continent, close enough for dispersal by power flight (unlikely) unless wind assisted or when the two were attached to Gondwanaland, then perhaps, migration. Proof might have to come from finding a relative of Dynastor darius darius in West Africa or if not, it’s ancestors migrational path up the South American continent.
    I haven’t read the other comments, sorry if I double up.

    1. Sounds plausible, but I wonder if too much time has elapsed? Gondwana was in place over 100 mya so would a mimic keep up the charade for that length of time without the original model present? This raises the general question: if an adaptation occurs in a species and suddenly the environment looses the motivation for the adaptation, how long would the adaptation persist?

  11. Butterfly and moth pupae can wiggle. I see it all the time. Shortly after the pupa is formed, there are still longitudinal muscles to let it wiggle. These generally eventually break down, and the pupa no longer wiggles until the adult is developed enough inside to have muscles and it can wiggle again.
    Some pupae never stop being able to wiggle. The pupa of a luna moth (inside its cocoon) will wiggle thru its period, near as I can tell. They are quite noisy, rustling around inside their cocoons.
    They are triggered to wiggle if they feel disturbed. I think they can sense if they are bumped, for example.

  12. We get Gaboon vipers in Zimbabwe, around the Eastern Highlands. I had a horror of them as a child – their camouflage is so good it made me scared of walking through leaf litter. I’ve never seen one – thankfully – although I’ve been hiking quite a bit around Chimanimani, where they’re not uncommon.

  13. Wow, that is just flat out amazing! Such a detailed snake mimic, I was even fooled myself by that first picture. Nature is so cool and endlessly fascinating.

  14. It doesn’t have to mimic any particular species of snake—just the eyes. Does anyone remember ever not knowing what an eye is or that when they are trained on you, the animal who owns them is looking at you? I would not know how to prove or disprove it, but the idea that many animals instinctively know what an eye is and its purpose doesn’t seem far fetched. One thing I would like to know is how mammal-like the eye has to be for, say, a human child to know what it is. For instance, does the young child recognize the eyes of spiders, which are somewhat unlike mammals?

Leave a Reply