1. george cauldron says

    Well, now I know what kind of critter lived in that shell I found on Catalina Island last summer…

  2. Rocky says

    Absolutely beautiful animal!
    Would love to have a underwater time machine for the period in history when cephalopods were common.

  3. ColinB says

    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?

  4. Rocky says

    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.

  5. says


    Any idea why my trackback attempts are getting throttled:

    Ping ‘’ 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?


  6. Niles says

    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 — .

  7. Trish says

    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? 2×0=0

    The first comment and answer my mother read in a book and brought it to my attention. What do you think?

  8. SEF says

    Such a lovely critter. I would say I want one, but I’m sure it’s much better off in the ocean.

  9. Neil says

    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.

  10. Trish says

    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)

  11. says

    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?!”

  12. NelC says

    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.)

  13. Shyster says

    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.