Friday Cephalopod: Argonauta nodosa
Category: Organisms • Science
Posted on: February 17, 2006 10:21 AM, by PZ Myers

Argonauta nodosa
Figure from Cephalopods: A World Guide (amzn/b&n/abe/pwll), by Mark Norman.
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Evolution, development, and random biological ejaculations from a godless liberal

PZ Myers is a biologist and associate professor at the University of Minnesota, Morris.
…and this is a pharyngula stage embryo.
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Category: Organisms • Science
Posted on: February 17, 2006 10:21 AM, by PZ Myers

Figure from Cephalopods: A World Guide (amzn/b&n/abe/pwll), by Mark Norman.
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Comments
nice bauplan on that mollusk
Posted by: CCP | February 17, 2006 10:25 AM
Well, now I know what kind of critter lived in that shell I found on Catalina Island last summer...
Posted by: george cauldron | February 17, 2006 10:52 AM
Holy crap! That's amazing!
Posted by: EVinson | February 17, 2006 10:55 AM
Absolutely beautiful animal!
Would love to have a underwater time machine for the period in history when cephalopods were common.
Posted by: Rocky | February 17, 2006 10:59 AM
It's beautiful!
Posted by: Tara Mobley | February 17, 2006 11:03 AM
Gorgeous. Where and how deep does that critter live?
Posted by: DurianJoe | February 17, 2006 11:38 AM
That is one pretty nautiloid!
Posted by: Chris | February 17, 2006 11:39 AM
Incredible!
Posted by: Squeaky | February 17, 2006 11:40 AM
Turns out this little beauty is actually an octopus!
Checkout http://www.nhm.ac.uk/hosted_sites/tcp/Argo.html
Posted by: ColinB | February 17, 2006 12:02 PM
I had to google it too, to see what it is. (I thought it looked like an underwater turkey, at first.)
Here's some good anatomical drawings:
http://tolweb.org/tree?group=Argonauta
Posted by: Apikoros | February 17, 2006 12:08 PM
Absolutely fascinating - does anyone know of any research into how it evolved the shell, and is it used for anything other than brooding the young (it would not seem strong enough for protection?).
Also, is it's relationship with jellyfish purely parasitic?
Posted by: ColinB | February 17, 2006 12:24 PM
Wow, it's beautiful!
Posted by: MissPrism | February 17, 2006 12:25 PM
Wow! That's a spectacular critter!
Posted by: P J Evans | February 17, 2006 12:55 PM
PZ, as the local cephalopod expert, would you know which Nautilid is considered the furthest evolved/advanced type?
I'd love to do some reading on that.
Posted by: Rocky | February 17, 2006 1:26 PM
PZ,
Any idea why my trackback attempts are getting throttled:
Ping 'http://scienceblogs.com/cgi-bin/MT/mt-tb.cgi/1228' failed: HTTP error: 403 Throttled
I also notice that trackbacks to both you and grrlscientist earlier did not happen automatically. Is there some global setting at scienceblogs that is inhibiting this?
Thanks!
Posted by: Steve | February 17, 2006 1:42 PM
Does anyone know if it's displaying those colours because they're default, 'hey, baby' display, or eek-gar-Getawayfromme! since it appears to be laying out an ink trail as well. (Which always reminds me of the secret ingredient on an Iron Chef episode -- Squid ink -- .
Posted by: Niles | February 17, 2006 2:36 PM
In other evolution news
http://www.cnn.com/2006/TECH/science/02/17/tiger.poo.reut/index.html
My cat's shit repels my wife and I pretty well. I didn't know we could make a bunch of money by selling it as an anti-burglar treatment.
Posted by: Great White Wonder | February 17, 2006 2:52 PM
Oh hell I don't know how to get in touch with you. I use a hotmail email.
Sorry for the derailment PZ but something is bugging me and I wanted to ask you about it.
Here goes:
If it takes 60 seconds for a glass to fill, and the quantity in the glass doubles every second, at what second is the glass half full?
59 right?
But how can that possibly be right if the glass was empty? 2x0=0
The first comment and answer my mother read in a book and brought it to my attention. What do you think?
Posted by: Trish | February 17, 2006 3:38 PM
Such a lovely critter. I would say I want one, but I'm sure it's much better off in the ocean.
Posted by: SEF | February 17, 2006 4:33 PM
Everyone has bet me to it, but I'll say it anyway: WOW. That's seriously a beautiful animal.
Xavier
Posted by: Xavier | February 17, 2006 4:39 PM
I've always been intrigued by the peculiar resemblance of the argonaut "shell" to the shells of cephalopods with whom it is distantly related (nautiloids, ammonoids).
The shell of the argonaut/paper nautlius is NOT homologous with the molluscan shell of bivalves, gastropods, scaphopods and other shelled cephalopods (living or extinct) but is produced in a unique manner by a gland found on the dorsal arms of females.
It is almost as if a group of snakes evolved a set of legs independently from the tetrapod limb.
Is this some form of class level morphic resonance ?
Naef, in the 1930s, proposed a marvellous "just so story" account involving some "hermit octopods" occupying the shells of deceased ammonites, evolving a set of calcifying organs to repair or reinforce the borrowed shell, then (after a sudden post-Cretaceous paucity ammonite real estate) building their own damn ammonite shells, whose form they apparently have continued to mimic for last 60 some odd million years.
I'd like to see Sheldrake come up with an idea THAT far out!
For a full account of Naef's hypothesis and an updated version by Young from the 1990s, read this article from the Tree of Life project.
I'm always amused by the creationist charge that the evolution community rests atop a lumpy rug stuffed with sandal-crushed trilobites and polystrate whales. If they knew what the REAL evolutionary dilemmas were maybe they'd quit with the griping and truly appreciate the breadth and beauty of the living world, for once.
Posted by: Neil | February 17, 2006 5:36 PM
Trish, every glass starts empty. It's Xeno's lesser known Beer-Glass Paradox.
Posted by: NelC | February 17, 2006 5:42 PM
Oh, and back on topic, that is one pretty cephalopod, PZ.
Are its arms in a defensive posture?
Posted by: NelC | February 17, 2006 5:43 PM
Awwww c'mon guys give a layperson some slack here. Someone else told me for it to be full at 60 seconds it needs to start off being 0.000000000000000086736173798840% full.
(beer sounds good though)
Posted by: Trish | February 17, 2006 8:15 PM
That really is a beautiful creature. But I have to admit that as I scrolled down my first reaction was a jaw-dropping "WTF is that?!"
Posted by: A Pang | February 17, 2006 8:24 PM
Sure, Trish, but you're not modelling a real-world situation, so don't sweat it. Even if there was a phenomenon that would actually double the quantity of liquid every second, from the molecular scale all the way up to the macroscopic, it would have to start with the glass being empty and a single molecule being added, then two at the next tick, then four, etc.
If it was a half-litre glass and you were adding water, then that 8.6 x 10^-19th proportion after the first second would still contain roughly 14 million H2O molecules. (If I've counted on my fingers right.)
Posted by: NelC | February 17, 2006 8:43 PM
Ok thank you. Not including the finger counting that actually made sense. lol
Posted by: Trish | February 17, 2006 10:33 PM
Sorry, but you have screwed yourself and your arguments. That is way too beautiful to have just evolved. There had to be the hand of an Intelligent Designer in that. I now know that the ID is Tiffany Glass Works.
Posted by: Shyster | February 18, 2006 5:07 AM