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Underwater Spider Spins Itself an Aqualung 91

Posted by Soulskill
from the later-i'm-out dept.
sciencehabit writes "In the ponds of northern Europe lives a tiny brown spider with a bubble on its back. The 10-millimeter-long Argyroneta aquatica is the only spider in the world that spends its entire life underwater. But just like land spiders, it needs oxygen to breathe. So every so often, it leaves its underwater web home to visit the surface and brings back a bubble of air that sticks to its hairy abdomen. It deposits the bubble into a little silk air tank spun for the purpose. This 'diving bell,' researchers have now found, is not just a repository. It's actually a gill that sucks oxygen from the water, allowing the spider to stay under for up to 24 hours."
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Underwater Spider Spins Itself an Aqualung

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  • If it's a "gill", why is the bubble only good for 24 hours? Does it also diffuse back into the water over time, thus shrinking it?

    • Re:Only 24 hours? (Score:5, Informative)

      by milkmage (795746) on Friday June 10, 2011 @04:11PM (#36405124)

      here's a hint. the answer to your question is in the article

      "The researchers decided to try out a new technology: a tiny fiber-optic oxygen sensor called an optode. Only 15 micrometers in diameter, the optode was small enough not to rupture the diving bell when the researchers poked it through the webby membrane and measured how gases move across the bell's surface. The bell, they found, functions like a gill: As the spider removes oxygen from the bell by breathing it in, more oxygen flows in to take its place. This gives the spider a constant oxygen supply without requiring it to venture to the surface often. But after about 24 hours.....

    • by Zironic (1112127)

      Apparently the water pressure threatens to crush the bell after 24 hours.

    • by RemyBR (1158435)

      From the article:
      >But after about 24 hours, water pressure on the silk begins to collapse the bell, so the spider makes a break for the surface to grab another bubble.

    • Third paragraph of TFA:

      But after about 24 hours, water pressure on the silk begins to collapse the bell, so the spider makes a break for the surface to grab another bubble.

    • by Opyros (1153335)
      According to Not Exactly Rocket Science [discovermagazine.com]:

      The spider could live in its bubble indefinitely, were it not for the fact that nitrogen tends to diffuse out of it. This means that the bell eventually shrinks. It's why the spider still has to travel to the surface periodically to top up its home, and prevent it from collapsing.

      • by Anonymous Coward

        It's old news that these aquatic spiders use gas diffusion to extract oxygen from the water. (Maybe the measurements done here are more precise--but the original article is behind a paywall, alas.)

        A good explanation about nitrogen diffusing out of the bubble is found here (from possibly 2004): http://www.hansthiele.de/galerie/sonst/w-spinne.htm [hansthiele.de]. I'll do a quick transcription.

        The bubble (like the air) contains about 21% oxygen and 78% nitrogen. The proportion of these gases in the water is about the same (1/

  • You know that's actually very awesome, more awesome than Aquaman then again it's not hard to be more awesome than Aquaman.
  • by jollyreaper (513215) on Friday June 10, 2011 @04:13PM (#36405150)

    Sitting on a cob web
    eyeing minnows with bad intent.
    Water running down his setae
    greasy palpae smearing mandibles.
    Floating in the cold lake
    Watching as the silly tadpoles run.
    Feeding on a dead duck
    spitting out pieces of his broken web.
    Aqualung!

    • Dammit, the one time I don't have mod points. The riff was the first thing to pop into my head when I read the headline, so kudos to you, sir.

  • Evolutionary Path (Score:2, Interesting)

    by Anonymous Coward

    Sometimes I like to try to guess what the evolutionary path of certain animals could have been.

    This is one case where I go "WTF?".

    • Probably started out eating water-surface insects, then learned to dive after swimmers/larva. Which it had mostly to itself in many cases, and surfacing brings it into range of predators that handle a wide variety of spiders, so at that point the push is to stay underwater longer.

      • by Culture20 (968837)

        Probably started out eating water-surface insects, then learned to dive after swimmers/larva. Which it had mostly to itself in many cases, and surfacing brings it into range of

        ...its evolutionary forebears (waterwalking spiders) who probably ate their diving kin.

  • They've (re-)discovered osmosis.

    Spider breathes oxygen-rich air. Spider exhales air with low oxygen content. Air with lower oxygen content than the water pulls oxygen from the water. Isn't that amazing?!

    • by shish (588640)
      That the osmosis happens faster than the oxygen gets used up seems pretty cool to me - why can't we do that to stay underwater for extended periods?
      • by Culture20 (968837)

        why can't we do that to stay underwater for extended periods?

        Because our poop isn't silk. Don't try to weave it into cloth either. I threw a baby diaper at a weaver in Ultima7 and she never spoke to me again.

      • That the osmosis happens faster than the oxygen gets used up seems pretty cool to me - why can't we do that to stay underwater for extended periods?

        Because we're a lot larger than those spiders? Tiny Asian women can scuba dive with 40cf cylinders longer than I can stay down with 72cf cylinders...coincidentally they're around twice as small as I am.

        I'm quite good at regulating my breathing but I have twice as much tissue to keep oxygenated.

      • Re:Oh look... (Score:4, Informative)

        by ChrisMaple (607946) on Friday June 10, 2011 @09:50PM (#36408046)

        Something that pops up again and again in various scientific and engineering endeavors is the "cube-square law". This law reflects properties that scale as area versus properties that scale as volume. In the case of the spider's osmotic sack, if we scale the sack up from spider size ( 1 cm ) to human size ( 2 m ), 200X, the sack's area increases by 200^2 = 40000 while the living being's body mass ( and presumably its metabolic activity ) increases by 200^3 = 8000000. If the sack's osmotic rate is just barely good enough for the spider, it is only 40000/8000000 = 0.005 of good enough for a human if both the sack and the human are scaled up by the same amount from spider-size.

        To use a technology similar to the spider's for humans, it either has to be scaled up disproportionately or changed in some major manner (like pleating the sack, using forced water flow to provide more dissolved oxygen, using a better osmotic membrane, etc.

    • by rustl (49621)

      They've (re-)discovered osmosis.

      This is just plain old diffusion, osmosis is a bit more specific, it being diffusion across a semi-permeable membrane. The air-water interface doesn't count.

  • This is intelligent design in effect!
    • by Creedo (548980)
      Um, no.
    • by osu-neko (2604)
      Nature is not, properly speaking, intelligent. Just more intelligent than most creationists...
  • This is not exactly news, is it? This spider's ancestors have been using the technique for a very long time. And it's not like this spider was recently discovered.

    • by tonywong (96839)
      This is what happens when people don't RTFA. The spider is not new, it's the research into the spider's behaviour that is new.

      "Previous researchers thought the spiders had to replenish their air every half-hour, but as they report online today in the Journal of Experimental Biology, Seymour and Hetz found that the spiders can hang out near their bells for up to a day, waiting for prey while keeping safe from birds."
  • the only spider in the world that spends its entire life underwater

    it leaves its underwater web home to visit the surface

    I don't know about everyone else, but I'm more impressed that it is able to die when it leaves the water and then re-animate itself when it comes back.

    Zombie Spiders!

    • by osu-neko (2604)

      the only spider in the world that spends its entire life underwater

      it leaves its underwater web home to visit the surface

      I don't know about everyone else, but I'm more impressed that it is able to die when it leaves the water and then re-animate itself when it comes back. Zombie Spiders!

      Yes, that's certainly a more plausible interpretation than that it merely visits the surface without leaving the water.

  • Not only the water breathing part, that also that its abdomen is on its back. Or is it the other way around?

  • In Hungary we even had a cartoon series about this spider and it was my favorite, it was called "Aqua Spider - Maverick Spider"

    Basically it shows the lives of various bugs and small animals around a lake and in it (under water) It was very educational, explaining what little critters were in a lake, what they did, how did the spider survived under water (real valid scientific explanations on a kids level)

    There are two spiders, one of them is a regular one and the other is the Aqua Spider, the serious starts

  • How does an air-breather possibly develop this mechanism to survive underwater?

    I believe in evolution, but sometimes am simply astounded.

    • By watching scuba divers.

      Note that the spider isn't the only thing that does this. There are several waterbugs that build bubbles underwater, that aren't spiders.

      They probably evolved from something that lived in the water but breathed somehow at the surface, like mosquito larva do. From that to pulling a bubble underwater doesn't seem too far a change.

    • by Creedo (548980)
      The likeliest scenario is probably a diving spider which dragged air bubbles with it on silk. The shape of the silk would alter towards a sphere over time, and the addition of the osmosis was just a happy accident which became incorporated in the adaptations.
  • Okay, it requires oxygen to breathe, so it goes to the surface to get air.

    They they say it's diving bell isn't just that, but an "aqualung" that allows it to get oxygen from the water.

    If it can get oxygen from that water, why is it going to the surface then for oxygen?

  • I hardly ever log in, but I had to give this effort a comment.! Well done jollyreaper :-)

  • ... for that spider to stay submerged while dragging an air bubble around.

  • Did anyone else notice the similarity between this and the fantasy physics of the Spelljammer [wikipedia.org] D&D setting? Specifically, read the paragraph Gravity and Air [wikipedia.org]. Deathspider FTW!
  • Eying little girls with bad intent. /an underwater goat with an aqualung

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