Cartwheeling Spiders

I smiled when I saw this article on newly discovered cartwheeling spiders.   The linked video is primarily about a robot, but there is a short sequence of the spider in action.    The best way I can describe my reaction is being proud of the spider.    I really have a high respect for spiders.   I love it when they are found to do something new.

This specific spider species lives in the Morroco desert, but it looks familiar.    It is able to switch to a mode of locomotion that allows it to travel twice as fast across level ground and even uphill.   This is a tumbling motion that appears remarkably sophisticated given the need to launch into the air with the dangling legs positioned just right to land in a way to complete the circular motion.

The spider moves this way because it is capable of moving this way.    Supposedly, it only moves this way when it feels threatened and needs to flee.    We don’t know what it does when people aren’t around.   We assume it doesn’t do this just for fun at times.   In any case, this is all hardwired in its genes somehow so the behavior gets located as part of what makes it a different species.      The scientists seem delighted to find that there are other physical distinctions to make a separate species (in this case incompatible sex organs with a similarly behaving spider).

As I have suggested in earlier posts, I am very reluctant to accept that this could be mindless behavior.   In particular, when it comes to spiders my default assumption is that they are intelligent beings.    They live in their world in a similar way I live in my world.   Likewise, we both make the best with what we have to work with.    I for example find delight and dancing my fingers across a keyboard.  This newly observed spider takes similar advantage of its ability to tumble.

The tumbling action would be impossible unless the legs were just the right size and would move in a way consistent with the tumbling action.    I argue that the presence of this architecture would not tumble unless the spider figured out it could do it.    The mind comes into this body and quickly figures out what the body can do, and then starts doing it.

In particular, I want to point out that there is more going on than just having the right machinery.   This form of locomotion is completely different from the usual spider walking.  The motion sets the entire body into a spinning coordinate system for the spider to maintain a situational awareness of where it is trying to reach or what it is trying to flee.    The spider is able to navigate while cartwheeling.     It is one thing to say that cartwheeling is possible, it is quite another to say that the spider is able to navigate while cartwheeling when its (and its ancestor species’) normal behavior is level walking.

In a recent post, I described the unique ability of animals to navigate through unexpected situations.   In that post, I suggested that even if we can automate vehicles for the full range of anticipated routes and hazards we will still want a human operator to be available to take over when something totally unexpected happens either in terms of unexpected hazards or of unexpected change in plans.  In that post, I claimed this ability to figure out reasonable courses of action is not unique to humans.   All living things have to figure out how to negotiate with an indifferent world.    They all do it.

Here is an example of a spider doing it.   In my knowledge, it joins the flying snake being able navigate in mid-air given its novel ability to contort its body into a more aerodynamic shape for gliding.   There is a huge differences in the neurology of spiders and snakes, but here they are doing essentially the same thing.    Both are navigating while using a form or locomotion that is not their normal mode and is new relative to their ancestor species or close relatives.    The snake’s ability to glide would be worthless unless it could reach a favorable landing spot.   The spider’s ability to tumble would be worthless unless it could reach a favorable location.  In both cases, these novel approaches need to be used selectively when it makes the most sense to use them.

In the post on autonomous vehicles, I mentioned how our initial expectations for artificial intelligence was backwards in assuming that uniquely human accomplishments would be harder to reproduce than common animal behaviors.   It turns out to be far more difficult to emulate basic animal behaviors.   In particular, it is very hard to emulate the ability of even the simplest organism to navigate its world: to move between a disadvantageous location to a more advantageous location.    That article about the spider includes a video that is a metaphor of this particular lesson.    A scientist discovers the spider’s motion, then creates a robot that crudely mimics the same behavior.   However, the robot required a remote control.    It was easy to come up with the mechanism.  It was hard to come up with the navigation.

This particular robot is unlike the spider.   The spider’s entire body (including brain and sensory capabilities) is cartwheeling.   The robot is wheeled with a horizontally stable axle.    My bet is that if this robot becomes autonomous, it will be to attach a sensor platform to be fixed with the axle allowing for a nice stable image while the wheel rotates separately.   Such an invention may be very useful for us.    However, the spider was able to perform its navigation with its sensory and intelligence in the part that is spinning!

There is another thing going on too.   Apparently it didn’t take very long for the robot to be designed and built but it is going to take much longer to get the autonomous part designed and implemented.    In contrast, the evolution of the spider was able to figure it out the navigation details at the same time it was figuring out the new mode of locomotion.    It is possible that the sensory and processing mechanisms developed in parallel with the mechanical innovations.   I tend to think that the preexisting sensory and processing mechanisms were able to quickly take advantage of a mechanical innovation — just like humans do with their technologies.



2 thoughts on “Cartwheeling Spiders

  1. Another small wonder in this article

    Blackpoll warbler songbird, which weighs 4.2 ounces, can fly 1700 miles non-stop from New England to South America

    At first I marveled how such a small bird needing rapid wing movement to stay aloft can store enough energy to make that trip. It needs to store up energy before making the trip, and do so in both destinations in North and South American continents.

    But then I thought about the necessary navigational intelligence it would need to pack in that tiny brain already challenged for song and for survival in forests. The species somehow figured out that a trip across the ocean would be rewarded with finding land in opposite hemisphere for favorable seasonal climate. But more amazingly, the necessary skills for successfully making a round trip to return where it started are packed in a very tiny brain (or somewhere in that little body).

    I think like the cartwheeling spider it had to figure out navigation skills at the same time it evolved the capability to fly such long distances non-stop. Neither skill would be valuable without the other.

  2. Pingback: Rethinking instinct | kenneumeister

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