Spirals. It’s always spirals.


Whoa. This is a siphonophore colony, 15 meters in diameter, just floating in the ocean with tentacles dangling down to catch prey.

I read the whole thread and didn’t see an answer to the question that immediately popped into my head. This is a colonial aggregate of multiple siphonophore bodies linked together into a long string, but it has an overall form of a spiral. How? Is there local signaling going on to regulate the distance between the strands so that it spontaneously forms that structure, or is it an accident of currents? I’m going to guess the former, which would be most interesting, because it implies the existence of factors that lead to large scale form and is therefore the kind of process that would lead to more elaborate patterns of development.

Also, it’s so planar. Is this something the animal regulates, or is it just layers in the ocean maintaining it?

Comments

  1. Owlmirror says

    Somewhere in France, Vincent Fleury is experiencing a feeling of smug triumph.

  2. blf says

    The mildly deranged penguin says duck taping all the little stringy thingys together isn’t too much fun…

  3. Sean Boyd says

    PZ @5,

    Might this provide some sort of hint as to how multi-cellular organisms first formed?

  4. blf says

    She once claimed to have taught him everything he still doesn’t know — a remarkably coherent claim from the mildly deranged one — but insists she either has or knows where the duck tape is, and soon as she draws them up, the plans for the croplongstringthingy circle. He, on the other wing, doesn’t even have a feathered tuxedo, much less any understanding of the dynamics in getting cheese into the Massive Orbital Cheese Vault (called the MOON due her poor clay tablet styluspenguinship).

  5. blf says

    @6, No ducks back then, so no duck tape.

    (Yes, yes, I know “duck tape” has nothing to due with flying meals-on-wings.)

  6. astringer says

    Looks like it might be a tracer indicating (spiralling) downwelling from Ekman pumping to me. Each to their own discipline ; )

  7. madtom1999 says

    @6 probably no. Multicellular life probably actually occurred quite early on in evolution but in a co-operative collection of archaea in a non conjoined/organised way – several different mutually beneficent metabolic pathways growing together long before the benefits of actually physically joining together overcame the effort required for synchronicity.

  8. Sean Boyd says

    madtom1999 @11,

    Thank you for the answer! So more like the Volvox that Fierce Roller writes about, then. Which is, of course, why he studies it.

  9. says

    The planar part is easy — it’s floating on the surface. Some of the colony members are gasbags, essentially. Others are swimmers, the colony is motile, but I expect the shape is just a result of an eddy current. This is definitely a strange kind of organism. It’s basically a long string of clones, but even though they are clones they develop into different specialized forms.

  10. stroppy says

    Spirals…

    Some artists will try to tell you that it’s all about the cone, cube, and sphere.

    But Nova had an episode, way back when, claiming that it’s really about the spiral, polygon, sphere, helix, meander, and branch.

    I think this is the one, “The Shape of Things.”

  11. leerudolph says

    #13: “It’s basically a long string of clones, but even though they are clones they develop into different specialized forms.”

    It would be of interest to know the detailed sequence of “different specialized forms”, and how it varies with respect to (at least) two natural metrics on a spiral, namely, (1) distance along the spiral (which might either be the physical distance or, if the various different forms take up distinctly different amounts of room, the distance just in terms of sequence, and (2) distance on the surface. (My ability to render this in ASCII art is failing me.) If some sort of information travels between clones, regulating their development, whether that information travels “along” the organism(s) or “across” the surface of the seawater would presumably have effects on the sequence; so knowing about the sequence might help with figuring out stuff about such information/regulation (and/or the lack thereof).

  12. unclefrogy says

    I can’t help but wonder at what the seas would have been like before things got bigger and harder, before not much was bigger than zooplankton is today but before encrustations evolved
    what an amazing place to be in, earth!
    uncle frogy

  13. says

    @15: Well it isn’t really clear. Here’s an article about them in Wired.
    “Now, there is of course the question of exactly how the individual bodies communicate, for instance how the propulsive bodies work together to not only sense their environment, but move en masse—what with not having a brain and all. This is, Siebert says, “an enigma.”

    Even though the group that siphonophores belong to, Cnidaria (which also includes true jellyfish), evolved 500 million years ago, their nervous system remains very simple. Siphonophores “have along the stem one long axon, which probably propagates signals from one end of the colony to the other,” Siebert said. “But how they coordinate all this and how the whole colony appears to act as an animal, it’s really not well understood.” It may be a simple way of doing things, but they sure as hell have been doing something right over those half billion years, diversifying all manner of behaviors and physiologies to become one of the oceans’ most prolific organisms.”

  14. wzrd1 says

    I’d think either thermal sensing of light sensing for determining depth. As for sensing spacing, that’s a grand question! Why not get your feet wet and find out?
    Oh yeah, landlocked landlubber. ;)

    @17, I’d love to see what neurotransmitter(s) are used, along with if there are any modulators to add complexity to that single axon signaling.

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