Afternoon InquisitionScience

Sunday AI: Leaping Cockroaches

That’s not a quote from a Batman Episode; it’s a new species found in only one area in South Africa.  They were discovered by accident when two entomologists were sweep-netting a meadow. 

BOHN, H., M. PICKER, K.-D. KLASS & J. COLVILLE 2010.A jumping cockroach from South Africa, Saltoblattella montistabularis, gen. nov., spec. nov. (Blattodea: Blattellidae). – Arthropod Systematics & Phylogeny, 68 (1): 53-69.

As you can see from these photos, the cockroaches have unusual hind legs that are modified for jumping, just like a grasshopper.  (The authors christened this animal the “leaproach”, although I would have lobbied for “cockhopper” myself.)

Now, I know that a lot of people don’t count roaches in their list of favorite insects.  So, a roach that can bound around like a kangaroo, which –I- think is really cool, is probably a nightmare for some.  Humans are most familiar with pest roaches, but those species only make up an estimated 1% of total roach diversity.  The rest of the 4000 species of roaches are benign, and often essential to ecosystem health.

Roaches have an amazing amount of modifications to the basic roachy body plan that let them survive in all sorts of environments.  There are diving roaches, sand-burrowing cockroaches, wood-eating roaches, and bioluminescent roaches.  Frustratingly, there is little information in the paper about why these leaproaches might have left scuttling behind for leaping.  The biggest hint is that they are found hopping around in grasslands during the day, pretty much side-by-side with grasshoppers.  Being able to jump long distances to avoid predators and find new food sources is handy for both grasshoppers and roaches.

Regular roaches can jump pretty well; the common German cockroach Blattella germanica can jump distances of 4 cm without any special leg modifications.  It’s not hard to imagine that day-active roaches that could jump a bit farther might be selected for over many generations.

cockhopper

Leaproaches are a really neat example of convergent evolution. Convergent evolution describes what happens when species that are distantly related–a grasshopper and a roach, for example–become more similar in appearance or structure because of natural selection.

Convergent evolution is the reason why a salmon, a shark, and a dolphin have similar body shapes, while they are not closely related taxonomically.  The physical environment they live in shaped their evolution in similar ways to solve similar problems–moving through an aquatic environment, in this example.

The  leaproach in this photo clearly has several body changes that are analogous with what you see on a grasshopper–primarily enlarged hind legs and big eyes.

Why not enlarged front legs? Well, if you want to go forward, the direction your eyes and other sensory organs are pointed, large jumpy front legs are not that helpful.  Hind legs help to propel you in the right direction, plus you have 4 legs you can reach out in front as you jump to grab onto passing stems of grass and hold on.

Similar environment, similar environmental constraints, and TA DA!  Leaproaches.

How do you feel about leaping cockroaches?  What unusual body plan change on an animal would freak you out even more?

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bug_girl

Bug_girl has a PhD in Entomology, and is a pointy-headed former academic living in Ohio. She is obsessed with insects, but otherwise perfectly normal. Really! If you want a daily stream of cool info about bugs, follow her Facebook page or find her on Twitter.

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39 Comments

  1. Roaches don’t bother me much (though I don’t see them often in these parts, so maybe I’ve just never had the opportunity to acquire a sense of revulsion).

    If anyone discovers flying spiders, however, I’m going to have to change planets.

  2. Oh god! Jumping cockroaches! Flying spiders! Oh god no!!!
    And ticks. If ticks could fly! I can’t even write a complete sentence. I’m a veterinarian and I’m picturing a dog coming in with ticks swarming around it and getting in my hair. Jesus, I would shave my head.
    Though giant isopods are the worst. If those were household pests I would become some kind of sterile-room shut-in.

  3. @buggirl – not being an enytmologist – could you please explain in layman’s terms why this bug is a cockroach that leaps, as opposed to a grasshopper that has some ‘roachy’ characteristics? I’m afraid I don’t have enough knowledge about bugs to be able to tell the difference.

    It looks like a strangely-shaped / oddly coloured grasshopper to me.

    Also – just out of curiousity, how large is this insect? Just interesting to me that a relatively lage bug (at least it looks pretty big in the pictures) in a fairly populous place has never been documented before.

    Thanks!

    1. Those are great questions! Entomologists (*cough spelling cough*) separate insects into groups by a couple of primary characteristics: Mouthparts, wing specializations, and mode of growth (complete/incomplete metamorphosis) are some key characters.

      Now that there are molecular tools, we can create really elaborate maps that show how much each group has changed over time from ancestral insects.
      So, right now, we probably have the clearest picture of insect phylogeny that we’ve ever had. (more about phylogeny here http://www.ucmp.berkeley.edu/exhibit/introphylo.html )

      In this case, the body structure matches roaches, and they are clearly roaches because they create egg cases, which grasshoppers don’t do.

  4. When I was a teenager I came home from a midnight movie about 2 am, and walked into my room quietly without turning on the lights so as not to wake my police officer father. I therefore didn’t see the very large cockroach sitting on the top of the door to my room, and when I opened it he/she/it was knocked off and fell perfectly down the back of my shirt. Needless to say everyone in the house was awake in the next 15 seconds, and my father almost shot me with his .38. I don’t like cockroaches, flying or not! Brrrrr I hope these flying ones never hitch a ride on a boat over here.

  5. “What unusual body plan change on an animal would freak you out even more?”

    Sharks with frickin’ laser beams…

    To answer the first question, I really don’t like insects very much at all, so aren’t particularly fond of the idea of leaping cockroaches.

  6. Wouldn’t it be creepy if there were rats that lived on the floor of the ocean like crabs? And when you walked out into the waves, they would stick their pointy little noses out from under the sand and bite your toes with their sharp, jagged yellow teeth. EEEWWWWW!!! And then when you pulled out your foot the big old rat with the hairless tail would be hanging from your big toe!!!

  7. “What unusual body plan change on an animal would freak you out even more?”

    There was an episode of the old Aeon Flux shorts that featured aliens that seemed to be primates and bipeds like us, but they had evolved to walk on their forelegs and manipulate stuff with their hind legs. Super creepy.

  8. It doesn’t squick me out – I think because it really doesn’t look like a roach to me.

    I think grackles with grasping claws on the ends of their wings would probably freak me the frack out. Look into a grackle’s eyes – there’s a dinosaur there regretting he’s not big enough to eat you.

  9. @bug_girl:

    Usually, you don’t find two species in the same niche – Even a tiny advantage in one species should fairly rapidly lead to that species squeezing out the other in their competition over the same preferred resources.

    Yet these jumping cockroaches are described as gamboling about with the grasshoppers. Are they in separate niches because they’re going after two different foods even though they’re in the same space at the same time? Or is this a very rare example of two species in the same niche?

    How to make them even more freak-out inducing? How about a predator-saturation strategy like locusts or cicadas, where a near-infinite number would suddenly choke the lands and skies every eleven or thirteen years?

    1. At this point, they are so new to science not much is known about them. In proper entomologist fashion, they were killed, dissected, and described :)

      They are known to eat grasshopper feces, and more research is being done to answer just that question.

  10. Ok I’m not a scientist – I havn’t the faintest what the difference is between a cricket and a roach.

    “For a moment there, the link looked as thought you were going to make a District 9 joke …”

    Hell no – parktown prawns are no laughing matter.

      1. I’m from NM. We call Jerusalem crickets Children of the Earth out there. They are super cool, and pretty huge. The first time I dug one up I was like WTF is that!?!

        On a side note when I was kid we used to screw around in the storm drain tunnels (which are around 5 feet in diameter) and sometimes you wouldn’t be able to see the walls because they were *entirely* covered in cockroaches. It was like the walls would move and shimmer. On the plus side, I saw quite a few albino roaches, which was pretty cool.

  11. Not only does this cockroach show characteristics of Orthoptera (grasshoppers, crickets), but also characteristics of Mantodea(mantids).The two orders of insects, Orthoptera and Dictyoptera have many similar characteristis

    Dictyoptera includes three groups of polyneopterous insects – cockroaches (Blattaria), termites (Isoptera) and mantids (Mantodea).

  12. Let me think, what would freak me out… Oh yes, how about a finger-sized cricket with humonguous digging claws and functioning folding wings?
    like the Gryllotalpa gryllotalpa for example. (thanks wiki)
    Now if those were more common I’d leave Europe

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