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"Argonaut" Octopus Sucks Air Into Shell As Ballast

Posted by timothy on from the 8-legs-good dept.

audiovideodisco writes "Even among octopuses, the Argonaut must be one of the coolest. It gets its nickname — 'paper nautilus' — from the fragile shell the female assembles around herself after mating with the tiny male (whose tentacle/penis breaks off and remains in the female). For millennia, people have wondered what the shell was for; Aristotle thought the octopus used it as a boat and its tentacles as oars and sails. Now scientists who managed to study Argonauts in the wild confirm a different hypothesis: that the octopus sucks air into its shell and uses it for ballast as it weaves its way through the ocean like a tiny submarine. The researchers' beautiful video and photographs show just how the Argonaut pulls off this trick. The regular (non-paper) nautilus also uses its shell for ballast, but the distant relationship between it and all octopuses suggests this is a case of convergent evolution."

59 of 72 comments (clear)

  1. Convergent Evolution? by Shadow+Wrought · · Score: 2, Funny

    Nah. The Angels just mis-intrepeted the cocktail napkin with God's first specs on it. Then they had to go back and create the same design with hardware instead of software.

    --
    If brevity is the soul of wit, then how does one explain Twitter?
  2. That's not ballast. by jcr · · Score: 5, Informative

    Ballast is weight that counteracts buoyancy. By introducing air into its shell, the animal is adding buoyancy.

    -jcr

    --
    The only title of honor that a tyrant can grant is "Enemy of the State."
    1. Re:That's not ballast. by cycleflight · · Score: 1

      Unless the air is compressed into a liquid denser than water. Probably not what the octopus is doing... just saying.

      --
      "...And who wants to make buttprints in the sands of time?" ~Bob Moawad
    2. Re:That's not ballast. by jcr · · Score: 2, Insightful

      If it had the ability to liquify air, that would be far more interesting.

      -jcr

      --
      The only title of honor that a tyrant can grant is "Enemy of the State."
    3. Re:That's not ballast. by Sir_Lewk · · Score: 1

      By rocking at the surface, the argonaut can also trap a sizeable volume of air, which, in turn, allows it to reach a greater depth before becoming neutrally buoyant. Finn and Norman think that this may allow these unusual octopuses to avoid the surface layers of the ocean, where they would be vulnerable to birds and other top-level hunters.

      I have to say, I am a little puzzled by this.

      --
      "linux is just DOS with a UNIX like syntax" -- Galactic Dominator (944134)
    4. Re:That's not ballast. by ivandavidoff · · Score: 1

      Ah! So it's not just me.

      Both these passages from the article are exactly backwards:

      By rocking at the surface, the argonaut can also trap a sizeable volume of air, which, in turn, allows it to reach a greater depth before becoming neutrally buoyant.

      The animals created air pockets as they would in the wild but without the ability to dive to the right depth, the air just brought them back to the surface again.

    5. Re:That's not ballast. by Rene+S.+Hollan · · Score: 2, Informative

      Nope.

      The argonaut traps air, and then forcefully descends to depth. So long as it has not reached the appropriate depth, it has to keep thrusting itself downward with it's jet, but once there, it is neutrally buoyant and no further expenditure of energy is required.

      It if can't get deep enough, then ultimately it will tire and the buoyancy will bring it to the surface again.

      --
      In Liberty, Rene
    6. Re:That's not ballast. by Daniel_Staal · · Score: 5, Informative

      As the pressure increases with depth, the volume of the air will decrease as it is squeezed into a smaller space. Buoyancy is determined by density, which is mass per unit volume. Mass is staying the same, but volume is decreasing.

      Above a certain depth, they will be be positively buoyant, and rise. Below that depth, they will be negatively buoyant, and sink. They gather enough air to be neutral at a certain depth, and stay there. The more air they gather the lower that depth is. If they can't get deep enough, they will tend to rise back to the surface (unless they vent air).

      The article is right.

      --
      'Sensible' is a curse word.
    7. Re:That's not ballast. by Rene+S.+Hollan · · Score: 1

      Damn. Its, not "it's", above.

      --
      In Liberty, Rene
    8. Re:That's not ballast. by Rene+S.+Hollan · · Score: 1

      Right, but this is a point of unstable equilibrium: if they rise too high, they will have to expend effort to return to neutral buoyancy depth, and if they dive too deep, they will have to expend effort to rise again. Still, if the alternative is having to prevent one's self from sinking all the time, it's probably less work.

      Also, the deeper they want to hover, the harder they have to struggle to get there.

      --
      In Liberty, Rene
    9. Re:That's not ballast. by CoryD · · Score: 2, Interesting

      And here I thought in submarine movies the term, "blow the ballast tubes" indicated releasing sea water that is held inside the tubes to allow for bouyancy. Hence, allowing for a sharp decrease in depth. So yes, while "ballast" does indicate a weight keeping a ship or object submerged, it can also be used as a "ballast tube" that causes lift.

    10. Re:That's not ballast. by ivandavidoff · · Score: 1

      Ok, now I get it. As you said, if it captures less air, the overall volume of the argonaut is reduced -- and density increased -- too quickly, making it neutrally buoyant at a lesser depth. The extra-large air bubble keeps the argonaut from shrinking too much before the desired depth is reached.

      I did a little quick reading to cure my ignorance and learned that divers have a device called a buoyancy compensator that works the same way.

    11. Re:That's not ballast. by pixelpusher220 · · Score: 2, Informative

      From the comments on TFA: As the Argonaut decends, the volume of air decreases under the increased water pressure. That causes the air to be less buoyant. So with more air, the air pocket maintains its buoyancy force for deeper dives. The Argonaut still has to 'force' its way down to the depth of neutral buoyancy though.

      Also from the comments, the Nautilus traps more air and has a hard shell so they can resist the water pressures more than the Argonauts. This allows the Nautilus to dive to deeper depths than the Argonaut.

      --
      People in cars cause accidents....accidents in cars cause people :-D
    12. Re:That's not ballast. by MasterPatricko · · Score: 2, Interesting

      Yes, a buoyancy control device (BCD) - usually an inflatable vest connected to your air cylinder - is standard diving equipment.

      Scuba divers will know that to stay neutrally buoyant, as you dive deeper, you must add extra air to your buoyancy control vest, and vent air when rising.

      Being neutrally buoyant is an unstable equilibrium, so if you are changing depth and do nothing or if you get your correction wrong, you end up rising/sinking even faster.

      If you do maintain your buoyancy well, your energy usage (for example for divers, as measured by your air usage) is hugely reduced - it makes sense to get it right if you plan to spend significant time at a roughly constant depth.

      The only difference in this case, is that the argonaut has no easy push-button to change buoyancy mid-dive, and instead has to return to the surface every time.

      --
      I'd tell a UDP joke, but you may not get it. I'd tell a TCP joke, but I'd have to keep repeating it until you got it.
    13. Re:That's not ballast. by jcr · · Score: 2, Interesting

      When you "blow the tubes" you're using compressed air to force the water out. The water is the ballast.

      -jcr

      --
      The only title of honor that a tyrant can grant is "Enemy of the State."
    14. Re:That's not ballast. by MadnessASAP · · Score: 1

      Well to be accurate it does need to continue to expend energy since it's at an unstable equilibrium. (to low and it will keep sinking, to high and it will float to the surface) But the energy required is far less then what it takes to reach that depth in the first place, or to maintain that depth if it didn't have the air bubble.

      --
      I may agree with what you say, but I will defend to the death your right to face the consequences of saying it.
    15. Re:That's not ballast. by ceoyoyo · · Score: 1

      Here I read that an octopus was using air in it's shell as ballast. I knew it was a bad sign when I read that shell was "paper thin." And it turns out that yes, there is no such thing as an octopus that can liquify air.

    16. Re:That's not ballast. by Rene+S.+Hollan · · Score: 1

      To be equally pedantic, maintaining an unstable equilibrium requires expenditure of energy only if disturbed (and I addressed this in a separate sub-thread), though disturbance is expected to happen. But "at the appropriate depth" as I wrote, it does not need to expend energy. Staying there, of course, is a practical impossibility.

      --
      In Liberty, Rene
    17. Re:That's not ballast. by Lotana · · Score: 1

      You need to read the parent carefully before replying:

      Hence, allowing for a sharp decrease in depth.

      Decrease in depth == submarine rises.

    18. Re:That's not ballast. by CoryD · · Score: 1

      When you "blow the tubes" you're using compressed air to force the water out. The water is the ballast.

      -jcr

      "indicated releasing sea water that is held inside the tubes"
      "ballast" does indicate a weight keeping a ship or object submerged"
      You don't say, clearly I missed that and didn't articulate that point.

    19. Re:That's not ballast. by Phoenixlol · · Score: 1

      Uh, yeah it's

    20. Re:That's not ballast. by Phoenixlol · · Score: 1

      My bad, was looking at GP, but in all fairness, u fucked it up too

  3. Mating Rituals by Anonymous Coward · · Score: 1, Funny

    Gives the term "Break it off inside her" a whole new meaning...

    1. Re:Mating Rituals by ivandavidoff · · Score: 2, Funny

      There's ugly, there's coyote ugly, and there's argonaut ugly.

    2. Re:Mating Rituals by somersault · · Score: 4, Funny

      The arm doubled as a penis, snapped off during sex and stays inside the female’s body.

      Yep, this has happened to me quite a few times. I'm just glad these things grow back!

      --
      which is totally what she said
    3. Re:Mating Rituals by Alsee · · Score: 1

      Do you have freakishly small arms, or do you date pachyderms?

      Either way, I hope never to find myself in bed with one of your ex-girlfriends.

      -

      --
      - - You can't take something off the Internet! That's like trying to take pee out of a swimming pool.
    4. Re:Mating Rituals by inKubus · · Score: 1

      ...tiny male (whose tentacle/penis breaks off and remains in the female)

      Or "octopussy", as we like to call him.

      --
      Cool! Amazing Toys.
  4. Sounds familiar by adeft · · Score: 1

    "after mating with the tiny male (whose tentacle/penis breaks off and remains in the female)." I have some friends that act like this whenever they get a new girlfriend

    1. Re:Sounds familiar by Bugamn · · Score: 1

      That sounds terribly painful.

    2. Re:Sounds familiar by Chih · · Score: 1

      Most of my friends only lost their balls

      --
      For best results, avoid doing stupid things.
  5. Neato (: by DarkKnightRadick · · Score: 3, Interesting

    And for it's next trick, the octopus will change its color!

    Oh wait, some already do that.

    --
    "There is a way that seems right to a man, but its end is the way of death." Proverbs 16:25 (NKJV)
    1. Re:Neato (: by Anonymous Coward · · Score: 1, Interesting

      I see your octopus and raise with cuttlefish

      Full NOVA episode

    2. Re:Neato (: by DarkKnightRadick · · Score: 1

      Doh!

      --
      "There is a way that seems right to a man, but its end is the way of death." Proverbs 16:25 (NKJV)
    3. Re:Neato (: by BitZtream · · Score: 1

      Yea, and plenty of fish have air bladders.

      --
      Persistent Volume manager for Kubernetes - https://github.com/dwimsey/openshift-pvmanager
    4. Re:Neato (: by Abcd1234 · · Score: 1

      They can go much further than that. The Mimic Octopus mentioned in the article not just changes colour, but also shape, in order to mimic as many as *15* different species! Seriously, the octopus is creepily intelligent, doubly so in this case...

    5. Re:Neato (: by Lotana · · Score: 1

      Dreadfully sorry, but it is unwritten law here that must be followed.

      Cuttlefish

      Whenever something is mentioned that was covered by XKCD: There must be a link to it.

      I covered you this time. Be careful in the future. I hear that consequences are quite severe.

    6. Re:Neato (: by DarkKnightRadick · · Score: 1

      That is creepy.

      --
      "There is a way that seems right to a man, but its end is the way of death." Proverbs 16:25 (NKJV)
  6. I for one by Ka+D'Argo · · Score: 2, Funny

    hail our new submarine octopus overlords

    --
    Aw Frell this
    1. Re:I for one by HeckRuler · · Score: 1

      Fixed buoyancy underlords you mean.

  7. Re:This isn't news. by SQLGuru · · Score: 2, Informative

    The news is that we now understand how and why they do it.

  8. - wince - by Anne_Nonymous · · Score: 1

    >> whose tentacle/penis breaks off and remains in the female

    - wince -

  9. Ubuntu? by Saeed+al-Sahaf · · Score: 5, Funny

    "Argonaut Octopus" ... That's the new Ubuntu release, right?

    --
    "Who are in control, they are not in control of anything - they don't even control themselves!" - Glen Beck
    1. Re:Ubuntu? by K.+S.+Kyosuke · · Score: 1

      If Adobe decides to put AIR into their shell, I won't mind. If they tried to do that to me, I would bash them.

      --
      Ezekiel 23:20
    2. Re:Ubuntu? by bmo · · Score: 1

      No... it goes like this:

      Adjective; Animal with alliteration.

      Arreptitious Argonaut
      Perorating Paper Nautilus
      Oleaginous Octopus.

      See?

      --
      BMO

    3. Re:Ubuntu? by Chih · · Score: 1

      Sounds like a Mega Man boss to me

      --
      For best results, avoid doing stupid things.
    4. Re:Ubuntu? by syousef · · Score: 1

      "Argonaut Octopus" ... That's the new Ubuntu release, right?

      after mating with the tiny male (whose tentacle/penis breaks off and remains in the female).

      Yeah that sounds about right.

      --
      These posts express my own personal views, not those of my employer
  10. I beg to differ on definition of "Coolest" by Radtastic · · Score: 1

    "(whose tentacle/penis breaks off and remains in the female)"

    FAIL!

    --
    You stereotypers are all the same...
    1. Re:I beg to differ on definition of "Coolest" by Rene+S.+Hollan · · Score: 2, Interesting

      It grows back: "Males generally form a new hectocotylus in each new season."

      --
      In Liberty, Rene
    2. Re:I beg to differ on definition of "Coolest" by HeckRuler · · Score: 2, Funny

      Argonaut, Part Duex, bad to the bone!

    3. Re:I beg to differ on definition of "Coolest" by SleazyRidr · · Score: 1

      If I do a girl so hard that it breaks off, I'll consider that a pretty cool accomplishment.

      --
      Is 1563649 a prime number?
    4. Re:I beg to differ on definition of "Coolest" by lennier1 · · Score: 1

      Kinda like of Jeebs in Men In Black but he only was a dick whose head could grow back.

    5. Re:I beg to differ on definition of "Coolest" by harley78 · · Score: 1

      Do these Cephs live that long? Most Octos live only 1 breeding "season". Unless it's just the fems that live that short, IANACE. (ceph expert).

    6. Re:I beg to differ on definition of "Coolest" by RockDoctor · · Score: 1

      FAIL!

      It all depends on how you describe it. My palaeontology text book from 1983 describes the hectocotylus and it's intelligent pursuit of and penetration into the female as "Copulation by guided missile".
      HIT!

      What a living organism was doing in a palaeontology text book is another question, best addressed to "Mr Trilobite Eyes." But old Trilobite Eyes knew how to get the attention of a class of undergrads.

      --
      Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
  11. Debated for millenia? by pdxp · · Score: 3, Insightful
    From TFA (emphasis mine):

    Finn and Norman filmed and photographed live animals in the act of trapping their air bubbles, solving a mystery that has been debated for millennia.

    Somehow I am starting to think that exaggeration in the media goes too far sometimes....

    1. Re:Debated for millenia? by ivandavidoff · · Score: 4, Informative

      FTFA: No less a thinker than Aristotle put forward a hypothesis.

      That was about 2.35 millenniums ago.

    2. Re:Debated for millenia? by geekoid · · Score: 1

      You do know that 'millennium' has a mean besides being part of the name of Han Solo's ship?

      You do know that Aristotle had a hypothesis about these wonderful creatures?

      I guess the real question is: Why would I assume someone on slashdot read the article.

      --
      The Kruger Dunning explains most post on /. http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect
    3. Re:Debated for millenia? by SleazyRidr · · Score: 1

      I still think you have a right expect they'll at least read the summary, though.

      --
      Is 1563649 a prime number?
  12. Summary reads like a Japanese Erotic novel by mjwx · · Score: 1

    "Even among octopuses, the Argonaut must be one of the coolest. It gets its nickname -- 'paper nautilus' -- from the fragile shell the female assembles around herself after mating with the tiny male (whose tentacle/penis breaks off and remains in the female)

    I cant have been the only person to notice.

    I have to ask, why does an article on the creatures propulsion system require a detailed and graphic description of the creatures reproduction method? Surely this information could have been buried in the article for people to read at their leisure.

    --
    Calling someone a "hater" only means you can not rationally rebut their argument.
    1. Re:Summary reads like a Japanese Erotic novel by OolimPhon · · Score: 1

      You're new here, aren't you?