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Giant African Rat Kills With Poisonous Mohawk 97

Posted by samzenpus from the T-approved dept.
thebchuckster writes "The African crested rat has been known to kill local dogs, but researchers have just figured out how. After eating the 'poison-arrow plant,' the over-sized rodent stores its poison-laced spit in special hollow hairs in its mohawk. Then, when a predator grabs the rat, the animal gets stung with the poison and spit-tipped hairs which can sicken and kill."
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Giant African Rat Kills With Poisonous Mohawk More

Giant African Rat Kills With Poisonous Mohawk

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  • Now that's punk.

  • Is this tool use? (Score:3)

    by es330td ( 964170 ) on Wednesday August 03, 2011 @06:11PM (#36978996)
    I realize it isn't termite fishing with a stick like monkeys do but it is certainly manipulation of an object for the animal's benefit.

    • Re: (Score:2)

      by blair1q ( 305137 )

      Only if the rat bought the quills at the Home Depot.

    • I wouldn't call chewing bark tool use. Nor grooming. It's "manipulation" only in the broadest sense of "using", but eating food is "using" an object for the animal's benefit.

      Regardless of semantics, it is doubtful this is a sign of intelligence (which tool use is usually taken to suggest).

      However it is a sign of awesome. Punk rock murder rats? Hell yes.

      • Re: (Score:1)

        by shugah ( 881805 )
        The article says the behavior seems to be hardwired into the rat's brain; that is, it's instinctive.

        Chimpanzees have to be taught to fish for termites with a stick. Chimps don't have any evolutionary adaptation specific to fishing for termites (an opposable thumb is not specific to this behavior or even to primates). My understanding is that some populations of chimps (and even individuals within a population) learn / exhibit this behavior, others don't.

        The giant crested rat chews poison bark and gro

  • How did this evolve? (Score:4, Interesting)

    by improfane ( 855034 ) on Wednesday August 03, 2011 @06:11PM (#36979006) Journal

    It does make you wonder how something so specific could evolve, the relationship between a poisonous plant and then the distribution mechanism.

    I know that when I eat certain herbs, I sweat them out and smell strongly of that herb whereas other people I know are fine. I wouldn't be surprised if that is related, the rats that could not sweat out the chemicals died, those that could survived, the ones who sweated through barbs fared even better. Do animals that disperse poison even know it's a defensive mechanism?

    How can they evolve that knowledge? Or is it aggression that is evolved too? A poisonous rat that is passive will probably not survive (it might still get eaten if it kills its predator) whereas one that is aggressive can attack its predator before it eats it.

    What do you think?

    • It's a basic instinct to survive, I doubt the rats are aggressively using anything. Predator grabs rat to kill and the poison is released.

    • How can they evolve that knowledge? Or is it aggression that is evolved too? A poisonous rat that is passive will probably not survive (it might still get eaten if it kills its predator) whereas one that is aggressive can attack its predator before it eats it.

      In this example, aggression is not required. If an animal is killed but also kills the predator in the process, then the DNA of that animal will be more likely to survive via the increased likelihood of survival for it's relatives due to the death of a local predator.

      For example, mother and baby rats get attacked by a fox. One baby rat dies along with the fox. Now the mother and remaining babies have an increased chance of survival. Because they all share similar DNA, the DNA traits that killed the f

    • People seem to think evolution is akin to this situation: "I was walking down third street just past the bank when I looked down and found a 1999 series A twenty dollar bill that happened to appear on the ground about six inches from the no parking sign, so I picked it up and put it in my left pants pocket." Evolution is more along the lines of "I found some money on the ground."

      In this case, the rats probably evolved the hollow hairs for a reason (IIRC these aren't uncommon in the animal kingdom. Isn't pol

      • Re:How did this evolve? (Score:5, Interesting)

        by Chris Burke ( 6130 ) on Wednesday August 03, 2011 @07:25PM (#36979818) Homepage

        Polar bear fur isn't hollow, but it is transparent, and directs sunlight down to the bear's skin like a coat of fiber optic cables, which is basically what they are.

        But yeah, this isn't that unusual. Chewing and grooming are normal behaviors for rats. The hairs could have evolved for any number of reasons, and may have been quite different, maybe just specialized whiskers, before the poison plant made predator-poisoning the main selective pressure.

        There's other cases of this kind of thing. For example, hummingbirds and the flowers they feed from will often undergo runaway evolution where the hummer's bill will be specialized to feed on the flower's specialized form that only the hummer's bill will fit. Even more amazing, there's a species on a Caribbean island where the males and females aren't just different in plumage, but also very different in bill shape which is unusual. Each of the two sexes feeds exclusively from two different but closely related species of flower.

        The theory was that when the hummers first arrived on the island, there was only one species of flower, and the more aggressive males monopolized the flowers that had the highest nectar output while the females were stuck with the ones with lesser output. The result was that the higher output plants were cross-pollinated by the males while the lower output plants were pollinated by the females, setting the stage for the two populations of flowers to begin diverging into separate species, and for each sex of hummer to follow.

        I dunno, I thought that was neat.

      • Re: (Score:1)

        by shugah ( 881805 )
        This isn't exactly co-evolution because the toxin in the tree bark has evolved independently from the rat for reasons that benefit the tree - there is no co-dependence. Try co-evolution is where the dependency is mutual - such as with flowers and specific pollinators evolving together.

    • I know that when I eat certain herbs, I sweat them out and smell strongly of that herb whereas other people I know are fine. I wouldn't be surprised if that is related, the rats that could not sweat out the chemicals died, those that could survived, the ones who sweated through barbs fared even better.

      This is a common mistake made by people with a poor understanding of anatomy. Toxins in your body are excreted by your liver and intestines, not your skin.
      Your sweat glands are there to regulate your temperature and are in no way designed to expel toxins.

      People smell like things they've eaten because it's on their breath and on their hands.

      • http://en.wikipedia.org/wiki/Garlic [wikipedia.org]
        Garlic is known for causing halitosis, as well as causing sweat to have a pungent 'garlicky' smell, which is caused by allyl methyl sulfide (AMS). AMS is a gas which is absorbed into the blood during the metabolism of garlic; from the blood it travels to the lungs (and from there to the mouth, causing bad breath) and skin, where it is exuded through skin pores.

        • http://en.wikipedia.org/wiki/Garlic [wikipedia.org]
          Garlic is known for causing halitosis, as well as causing sweat to have a pungent 'garlicky' smell, which is caused by allyl methyl sulfide (AMS). AMS is a gas which is absorbed into the blood during the metabolism of garlic; from the blood it travels to the lungs (and from there to the mouth, causing bad breath) and skin, where it is exuded through skin pores.

          Yes, ok, some exogenous organic compounds make their way into sweat. But garlic is not a toxin, and the gas that gets to your pores is a byproduct, not a design feature of sweat glands. Since you obviously know how to use wikipedia, try reading the one on perspiration.

      • Really? I know if I eat curries/tajines with a lot of fenugreek in them the smell is strongest in my armpits.

        • OMG! Dude, that is waaaaaay TMI. I know this is slashdot, but c'mon.
        • Does this give you a breeding advantage?

          • If I stand next to someone long enough, it gives them a disadvantage ;-)

            • I often eat food with all that good stuff in it, was wondering if upping the dose would have certain pheronome-like effects, even if only on women from certain parts of the world.

              hmmmm, but not to smell like dinner in places where cannibalism was recently given up.....

      • No.

        I can eat foods that do not taste of a herb with a knife and fork and my skin smells very strongly of the herb - even if you could not smell the herb in the food.

    • It does make you wonder how something so specific could evolve, the relationship between a poisonous plant and then the distribution mechanism.

      I wouldn't be surprised if that is related, the rats that could not sweat out the chemicals died, those that could survived, the ones who sweated through barbs fared even better.

      Oh, and rats do not sweat. They regulate their temperature by constricting or expanding blood vessels in their tails.

    • It does make you wonder how something so specific could evolve

      First of all, the rat (Lophiomys imhausi) evolved into a non-rat, with a nice, cute, fluffy tail (see exhibit A [youtube.com]. That prevented them from being killed by humans. The poison quill adaption was just to piss off dogs.

    • If you read the fucking article, you'd know these weird rats chew the bark of the plant and then lick their fur to store the poison on it. They don't sweat the poison out.

    • My friend's hedgehog licked my hands and then started foaming at the mouth, and then spreading it on its quills. She explained:

      https://encrypted.google.com/search?q=self-annoiting

      If a hedgehog tastes something nasty, the froth it up and spread it on their spines. It works - if you get pricked hard, you can see a bit of an allergic reaction around the pricks (the spines are not like porcupines, ie, they don't have barbs. They're just somewhat sharp.)

      How can they evolve that knowledge? Or is it aggr

    • Re: (Score:2)

      by guruevi ( 827432 )

      There is no such thing as macro-evolution. The rat doesn't all of a sudden start eating poisonous plants and sweating them out.

      Most likely the selective pressure was made in several small steps:
      - There is less food at one point and the only thing left is poisonous plants. Some die of the plant, some die of hunger. Those that are somewhat 'immune' to the poison get to breed.
      - If there is less food for the rats, there is usually less food for the rest of the ecosystem as well. Things start eating or bringing

  • That the rat isn't from Sumatra.

  • Where can I get a Giant African Rat coat before PETA is all over me?

  • next thing... (Score:1)

    by Anonymous Coward

    he gets a starring role in the desperate A-Team 2: What else can we do to ruin Mr. T

  • Could be a cool pet. Bet no one ever tries to pet it without permission.

  • Whoa.

    I dated that chick.

    The 80s were cool...

  • Pity (Score:3, Funny)

    by ripdajacker ( 1167101 ) on Wednesday August 03, 2011 @07:00PM (#36979572) Homepage

    I pity the fool who touches my mohawk!

  • Damn nature, you scary!

  • Ratvis Bickle: [Ratvis is admiring his crest in the mirror] Huh? Huh?
    [Flexes]
    Ratvis Bickle: Faster than you, fucking son of a... Saw you coming you fucking... shitheel.
    [Crest Stiffens]
    Ratvis Bickle: I'm standing here; you make the move. You make the move. It's your move...
    [Lunges]
    Ratvis Bickle: Don't try it you fuck.
    [Reflexes]
    Ratvis Bickle: You talkin' to me? You talkin' to me? You talkin' to me? Then who the hell else are you talking... you talking to me? Well I'm the only one here. Who the fuck do you thi

  • So would rat poison (coumadin / warfarin) still work on these rats?

  • make quite the politician.

  • Summary is a bit inaccurate, leading to uninformed comments and questions on this thread. From the article,

    The researchers found that the rats chew the bark of the poisonous tree and lick themselves to store their poisonous spit in specially adapted hairs.

    They do not eat the plants. They chew it. This is the same way people chew certain herbs and then apply it to wounds to numb the pain. They don't eat those plants - if they did they'd be in poor health indeed.

  • http://en.wikipedia.org/wiki/Mithridatism [wikipedia.org] It probably starts with the Mother rats milk and continues with additional doses each time it chews the bark! As for the Adaption of the Back hairs, that probably happened when the Rats that had hair better able to absorb the saliva lived longer to have more descendents than the ones that got eaten early because their hair didn't hold enough poison to deter predators!

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