How the pebble toad rolls

The best part of being an evolutionary biologist is learning about the endless ways that animals adapt to their existence and environment.  (The classic aphorism is “Natural selection is cleverer than you are.”)

And here’s a behavior completely new to me: the escape behavior of the pebble toad, Oreophrynella nigra, from Bolivia and Guyana. The inimitable Attenborough tells the tale:

An article at BBC EarthNews notes:

The toad is so small and light that the forces of impact are too tiny to cause it any harm.

However, as well as being less than impressive jumpers, the toads do not swim well.

So while most that land in puddles survive, there are reports of toads drowning after tumbling into deeper pools of water.

h/t: Christopher


  1. gbjames
    Posted January 12, 2013 at 1:15 pm | Permalink


    like a toad landing in a deep pool.

  2. marycanada FCD
    Posted January 12, 2013 at 2:42 pm | Permalink


  3. Jim Thomerson
    Posted January 12, 2013 at 3:35 pm | Permalink

    Isn’t it Venezuela and Guyana rather than Guyana and Bolivia?

    • infiniteimprobabilit
      Posted January 13, 2013 at 3:02 am | Permalink

      That looks to me like Mount Roraima, on the borders of Brazil, Venezuela and Guyana, or possibly one of the other tepui mountains in the area. I don’t know if it’s identified in the program, which I haven’t seen. Searching for ‘Roraima’ or ‘tepui’ in Google Images brings up some spectacular pictures of those plateaux. (Angel Falls, the highest in the world, falls off the edge of one of them).

      • HaggisForBrains
        Posted January 13, 2013 at 6:40 am | Permalink

        “Angel Falls” as featured in the movie “Up”, which I’ve just been watching. Great film, BTW, repeated on BBC3 tonight at 8.00pm. No toads, I’m afraid.

        • infiniteimprobabilit
          Posted January 14, 2013 at 2:53 am | Permalink

          I remember reading of an ascent of the cliffs of one of those plateaux (apparently the government of whichever country was keen to sponsor this since a practical route up to the plateau would strengthen their territorial claim). Apparently the climb was more like an exercise in gardening, with showers of bromeliads descending from every ledge past those below. Unfortunately I can’t remember the title of the book. Oh, wait – “Climb to the Lost World” by [Googles] Hamish McInnes. The Lost World being of course a reference to Conan Doyle’s novel which was actually inspired by a similar plateau (Huancacha) in Bolivia.

          • HaggisForBrains
            Posted January 14, 2013 at 3:09 am | Permalink

            Yes, I had the good fortune to meet Hamish and some of the team members many years ago when I lived in Glencoe. Sadly his old cottage in the glen has been vandalised recently because of its association with paedophile Jimmy Savile. Some have called for the cottage to be demolished, but the local climbing community is resisting this, rightly claiming that its association with the climbing legend is more significant.

  4. Marella
    Posted January 12, 2013 at 3:43 pm | Permalink

    A toad that can’t swim or hop! It’s looks weird crawling along like that and I’d have thought it would have got a bit of gravel rash at least, extraordinary. I wonder how often the average Pebble toad has to pull this stunt?

  5. Posted January 12, 2013 at 3:53 pm | Permalink

    Soldier crabs (Coenobita clypeata, a largish species of terrestrial hermit crab) in the West Indies, who usually inhabit roundish marine snail shells, will tuck in their head and legs and roll downhill when disturbed. I’ve not observed them closely enough to see if they actually push off to start rolling, or just let go of the ground when they tuck in, so that the slope of the ground lets gravity do all the work.

  6. Scott Reilly
    Posted January 12, 2013 at 6:06 pm | Permalink

    Even if it tenses its body, it’s hard to see how banging its head off a rock wouldn’t hurt it in soem way. Amazing!

    Coursera a running a course in Animal Behaviour in the summer. It’s looks awesome

  7. marksolock
    Posted January 12, 2013 at 8:14 pm | Permalink

    Reblogged this on Mark Solock Blog.

  8. BillyJoe
    Posted January 12, 2013 at 8:54 pm | Permalink


    It sounds like you haven’t watched all of David Attenborough’s nature series. This excerpt comes from one of them. You are truly missing out if you haven’t.

  9. Torbjörn Larsson, OM
    Posted January 12, 2013 at 10:36 pm | Permalink

    Biology on small scales utilizing physics of small scales. Reminds me of seeing small insects trying to swim in the, for them, dense air.

    Speaking of biological implications, will we now see ROTFLtoads competing with LOLcats?

  10. Posted January 13, 2013 at 9:18 am | Permalink

    I sometimes think that the only thing cleverer than natural selection is BBC videographers and cameramen…that footage is typically amazing stuff, top-shelf!

  11. Posted January 13, 2013 at 6:12 pm | Permalink

    That is some amazing cinematography! The tarantula in the background that you don’t until it moves, because it’s out of focus behind the in-focus toad, the 1-inch toad in the foreground with the grand-canyon like background — all in focus. And it’s not as if you can give direction to toads and tarantulas. Amazing stuff purely from a photographic point of view.

    • Posted January 13, 2013 at 6:13 pm | Permalink

      That you don’t *see* until it moves, is what I meant to say.

  12. Posted January 14, 2013 at 8:11 am | Permalink

    Wow!!!! Coming late to this, but this is so wonderful for so many reasons having to do with evolution. The toad’s adaptive ability to roll and bounce, of course. The roving tarantula–an example showing that many spiders DON’T use silk to capture prey, although they are still dependent on silk for other important functions. The fact that the toads may drown after escaping from a predator–no adaptation is perfect; it’s all a game of odds, and these toads survive as a species not because they all individually escape predators but because just enough of them do. Here’s another example of a “rolling” adaptation.

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