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"Argonaut" Octopus Sucks Air Into Shell As Ballast

timothy posted more than 4 years ago | from the 8-legs-good dept.

Earth 72

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."

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72 comments

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At last! (0)

Anonymous Coward | more than 4 years ago | (#32269426)

At last, I was so dumbfound by this.

Convergent Evolution? (2, Funny)

Shadow Wrought (586631) | more than 4 years ago | (#32269500)

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.

Excuse me... (0)

Anonymous Coward | more than 4 years ago | (#32269504)

...but the distant relationship between it and all octopuses suggests this is a case of convergent evolution. ...but I think you mean "convergent divine intervention."

That's not ballast. (5, Informative)

jcr (53032) | more than 4 years ago | (#32269508)

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

-jcr

Re:That's not ballast. (1)

cycleflight (1811074) | more than 4 years ago | (#32269608)

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

Re:That's not ballast. (2, Insightful)

jcr (53032) | more than 4 years ago | (#32269708)

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

-jcr

Re:That's not ballast. (1)

ceoyoyo (59147) | more than 4 years ago | (#32273276)

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.

Re:That's not ballast. (1)

Sir_Lewk (967686) | more than 4 years ago | (#32269710)

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.

Re:That's not ballast. (2, Informative)

pixelpusher220 (529617) | more than 4 years ago | (#32270476)

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.

Re:That's not ballast. (1)

ivandavidoff (969036) | more than 4 years ago | (#32269714)

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.

Re:That's not ballast. (2, Informative)

Rene S. Hollan (1943) | more than 4 years ago | (#32269890)

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.

Re:That's not ballast. (1)

Rene S. Hollan (1943) | more than 4 years ago | (#32269908)

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

Re:That's not ballast. (1)

Phoenixlol (1549649) | more than 4 years ago | (#32285358)

Uh, yeah it's

Re:That's not ballast. (1)

Phoenixlol (1549649) | more than 4 years ago | (#32285388)

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

Re:That's not ballast. (1)

MadnessASAP (1052274) | more than 4 years ago | (#32272234)

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.

Re:That's not ballast. (1)

Rene S. Hollan (1943) | more than 4 years ago | (#32274634)

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.

Re:That's not ballast. (5, Informative)

Daniel_Staal (609844) | more than 4 years ago | (#32269906)

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.

Re:That's not ballast. (1)

Rene S. Hollan (1943) | more than 4 years ago | (#32269956)

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.

Re:That's not ballast. (1)

ivandavidoff (969036) | more than 4 years ago | (#32270128)

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.

Re:That's not ballast. (2, Interesting)

MasterPatricko (1414887) | more than 4 years ago | (#32270510)

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.

Re:That's not ballast. (0)

Anonymous Coward | more than 4 years ago | (#32276202)

Don't be silly, this is Slashdot, he who briefly remembers something about some thing from TV, or high school 10 years ago knows more about that thing than professional scientists.

You'd think that a site that has a heavy amount of technical and scientific content might attract people who don't instantly dismiss things from professionals who, you know, actually know something about their field of expertise, without at least checking to see if they are or aren't correct by looking up whatever it is they're dismissing. Unfortunately though, just spouting off about something you know nothing about is enough to get you modded up nowadays.

Still, thanks you Daniel for being one of those few who still knows what they are on about and are brave enough to post here in the face of ignorance and stupidity that now plagues the very community that is quick to sound off about how important scientific process and things like peer review are, all the while spouting crap for which there is no basis, and stating things that they simply can't back up with facts.

Slashdot needs something that goes above karma, a "Person who knows what the fuck he is on about" rank, that allows them to automatically get +5, so that their correct, valid, and insightful responses aren't lost amongst the shit, due to the fact the current system lets the same stupid people moderate as are spouting the stupid blatantly incorrect shit that gets modded up in the first place. This is why the average level of intelligence involved in a highly modded response has decreased in line with the increase ignorance of Slashdot's userbase, god knows where it would be without people like this at least being brave enough to keep the average up in some cases.

The same goes for moderators- if you don't know if that the post you are modding up really is correct because it is logically flawed, or it lacks proper explanation of it's conclusion, either research it and mod it down if wrong, up if right, or don't fucking mod it at all.

Re:That's not ballast. (2, Interesting)

CoryD (1813510) | more than 4 years ago | (#32269998)

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.

Re:That's not ballast. (0)

Anonymous Coward | more than 4 years ago | (#32270158)

No, blowing the ballast tubes releases sea water causing the submarine to rise. Diving is flooding the ballast tubes.

Re:That's not ballast. (1)

Lotana (842533) | more than 4 years ago | (#32274710)

You need to read the parent carefully before replying:

Hence, allowing for a sharp decrease in depth.

Decrease in depth == submarine rises.

Re:That's not ballast. (2, Interesting)

jcr (53032) | more than 4 years ago | (#32270680)

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

-jcr

Re:That's not ballast. (1)

CoryD (1813510) | more than 4 years ago | (#32277400)

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.

Mating Rituals (1, Funny)

Anonymous Coward | more than 4 years ago | (#32269510)

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

Re:Mating Rituals (2, Funny)

ivandavidoff (969036) | more than 4 years ago | (#32269768)

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

Re:Mating Rituals (4, Funny)

somersault (912633) | more than 3 years ago | (#32270940)

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!

Re:Mating Rituals (1)

Alsee (515537) | more than 4 years ago | (#32273058)

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.

-

Re:Mating Rituals (1)

inKubus (199753) | more than 4 years ago | (#32275700)

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

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

Sounds familiar (1)

adeft (1805910) | more than 4 years ago | (#32269514)

"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

Re:Sounds familiar (1)

Bugamn (1769722) | more than 4 years ago | (#32269888)

That sounds terribly painful.

Re:Sounds familiar (1)

Chih (1284150) | more than 4 years ago | (#32270366)

Most of my friends only lost their balls

Neato (: (3, Interesting)

DarkKnightRadick (268025) | more than 4 years ago | (#32269528)

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

Oh wait, some already do that [nationalgeographic.com] .

Re:Neato (: (1, Interesting)

Anonymous Coward | more than 4 years ago | (#32269960)

I see your octopus and raise with cuttlefish [youtube.com]

Full NOVA episode [pbs.org]

Re:Neato (: (1)

DarkKnightRadick (268025) | more than 4 years ago | (#32270468)

Doh!

Re:Neato (: (1)

Lotana (842533) | more than 4 years ago | (#32274738)

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

Cuttlefish [xkcd.com]

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.

Re:Neato (: (1)

BitZtream (692029) | more than 4 years ago | (#32272648)

Yea, and plenty of fish have air bladders.

Re:Neato (: (1)

Abcd1234 (188840) | more than 4 years ago | (#32274274)

They can go much further than that. The Mimic Octopus [wikipedia.org] 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...

Re:Neato (: (1)

DarkKnightRadick (268025) | more than 4 years ago | (#32276836)

That is creepy.

This isn't news. (0)

Anonymous Coward | more than 4 years ago | (#32269530)

They've been doing this for unknown zillions of years!

Re:This isn't news. (2, Informative)

SQLGuru (980662) | more than 4 years ago | (#32269626)

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

I for one (2, Funny)

Ka D'Argo (857749) | more than 4 years ago | (#32269564)

hail our new submarine octopus overlords

Re:I for one (1)

HeckRuler (1369601) | more than 4 years ago | (#32270646)

Fixed buoyancy underlords you mean.

Efficient riding of the EAC, dude. (0, Offtopic)

masterwit (1800118) | more than 4 years ago | (#32269610)

Crush: Okay. Squirt here will now give you a rundown of proper exiting technique.

Squirt: Good afternoon. We're gonna have a great jump today. Okay, first crank a hard cutback as you hit the wall. There's a screaming bottom curve, so watch out. Remember: rip it, roll it, and punch it.

Marlin: It's like he's trying to speak to me, I know it.

[to Squirt]

Marlin: Look, you're really cute, but I can't understand what you're saying. Say the first thing again.

---

I love Finding Nemo, with the whole "catching of currents" this sadly was the first thing to cross my mind :)

- wince - (1)

Anne_Nonymous (313852) | more than 4 years ago | (#32269740)

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

- wince -

You Fa1l It? (-1, Offtopic)

Anonymous Coward | more than 4 years ago | (#32269742)

to be about 6doinIg

Ubuntu? (5, Funny)

Saeed al-Sahaf (665390) | more than 4 years ago | (#32269762)

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

Re:Ubuntu? (1)

K. S. Kyosuke (729550) | more than 4 years ago | (#32269790)

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.

Re:Ubuntu? (0)

Anonymous Coward | more than 4 years ago | (#32269878)

Not enough alliterative allusion.

Octarine Octopus?

Re:Ubuntu? (1)

bmo (77928) | more than 4 years ago | (#32269924)

No... it goes like this:

Adjective; Animal with alliteration.

Arreptitious Argonaut
Perorating Paper Nautilus
Oleaginous Octopus.

See?

--
BMO

Re:Ubuntu? (1)

Chih (1284150) | more than 4 years ago | (#32270382)

Sounds like a Mega Man boss to me

Re:Ubuntu? (1)

syousef (465911) | more than 4 years ago | (#32270602)

"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.

Absent alliteration (0)

Anonymous Coward | more than 4 years ago | (#32272706)

Orange octopus is much more magnificent.

I beg to differ on definition of "Coolest" (1)

Radtastic (671622) | more than 4 years ago | (#32269848)

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

FAIL!

Re:I beg to differ on definition of "Coolest" (0)

Anonymous Coward | more than 4 years ago | (#32269872)

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

FAIL!

Doesn't the "octo" mean it has eight tentacles / penii?

If so, 7 still makes it a pretty cool dude.

Re:I beg to differ on definition of "Coolest" (2, Interesting)

Rene S. Hollan (1943) | more than 4 years ago | (#32270014)

It grows back [wikipedia.org] : "Males generally form a new hectocotylus in each new season."

Re:I beg to differ on definition of "Coolest" (2, Funny)

HeckRuler (1369601) | more than 4 years ago | (#32270652)

Argonaut, Part Duex, bad to the bone!

Re:I beg to differ on definition of "Coolest" (1)

lennier1 (264730) | more than 3 years ago | (#32271348)

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

Re:I beg to differ on definition of "Coolest" (1)

harley78 (746436) | more than 4 years ago | (#32275010)

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).

Re:I beg to differ on definition of "Coolest" (1)

SleazyRidr (1563649) | more than 3 years ago | (#32270784)

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

Re:I beg to differ on definition of "Coolest" (1)

RockDoctor (15477) | more than 4 years ago | (#32277922)

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.

AwesOme fp (-1, Offtopic)

Anonymous Coward | more than 4 years ago | (#32269922)

In any way related mXuch as Windows purposes *BSD is Don't walk around

Mega-Octopus-Maid (0)

Anonymous Coward | more than 4 years ago | (#32269936)

She's gone from suck to blow!

Debated for millenia? (3, Insightful)

pdxp (1213906) | more than 4 years ago | (#32270088)

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....

Re:Debated for millenia? (4, Informative)

ivandavidoff (969036) | more than 4 years ago | (#32270306)

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

That was about 2.35 millenniums ago.

Re:Debated for millenia? (1)

geekoid (135745) | more than 4 years ago | (#32270564)

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.

Re:Debated for millenia? (1)

SleazyRidr (1563649) | more than 3 years ago | (#32270818)

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

Summary reads like a Japanese Erotic novel (1)

mjwx (966435) | more than 4 years ago | (#32274474)

"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.

Re:Summary reads like a Japanese Erotic novel (1)

OolimPhon (1120895) | more than 4 years ago | (#32276388)

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