A query about feeding (for a palaeontology paper)

Discussion in 'Behavior and Intelligence' started by acutipuerilis, Mar 4, 2011.

  1. acutipuerilis

    acutipuerilis Larval Mass Registered

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    Hi All,
    A slightly odd request, but I thought you'd be the people to know... I've
    got some strange fossil remains that make me wonder if we've got the
    leftovers of a benthic nautiloid's dinner! Something in the Middle
    Ordovician has been selectively catching carpoid echinoderms and
    occasionally trilobites, and leaving piles of their remains in one spot.
    There is nothing resembling a faecal pellet - just acumulations of bits.
    So... 1) do octopus produce recognisable pellets, or just amorphous
    excretions? 2) do they have preferred feeding posts that they return to? 3)
    if their prey had something really robust (e.g. crab claws), would it spit
    those bits out whole?

    Many thanks - there's a pers. comm. in the paper for the most useful reply! :grin:
    Joe Botting
     
  2. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    Joe,
    I'll start but some of our divers may have more info about in situ observations (I keep small/medium small octopuses). Modern day octopuses (very little changes from as far back as we have found soft remains) have an esophogus that passes through the middle of their brain so they don't intentionally eat shells of any kind. Most have a radula that grinds the soft food to allow easy passages. According to a paper I read, one of the toxins is used to aid in breaking down the food so that it can be extracted from shells easily, leaving shells with little damage. Additionally, some of the larger octos are known to have midden piles of these shells and skins around their dens and divers will locate some species this way (vulgaris being the most noted).

    The four species I have kept have not created waste piles near their dens. They discard the shrimp skins and crab shells but not in a pile. The upper crab shell and claws are usually in tact but devoid of meat (they also discard the gills). I have not noticed any of the small legs in the tank so it is unclear if they eat these softer shelled parts or if the clean-up crew gets them. Shrimp are "pealed" and the shell retains its shape. Mollask shells remain hinged.

    In the wild many octopuses will live in a den for a period of time and then move. Some have been observed repeatedly using multiple dens at one time (in one paper I read it suggested this kind of den use as resting spot during daily foraging). Octopuses that create middens outside their dens are known to bring the food home to eat but in IME the smaller species don't seem to do this, however, they do seem to take their food to a place close to their den and settle to eat there.
     
  3. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

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    Extant Nautiloids eat arthropod molts, not that the extinct ones did. Sounds like a great paper!
     
  4. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    Oh, I forgot to answer about pellets but you likely extrapolated that from my answer about shells. The answer is no, they excrete a soft worm looking tube. I briefly look for the two photos that are somewhere in the forums but could not come up with a link.
     
  5. acutipuerilis

    acutipuerilis Larval Mass Registered

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    Thanks very much for that - it's pretty much what we figured was the situation. It's amazing how little effort seems to have gone into interpreting fossils as "nautiloid pellets" in the palaeontology literature - basically, any evidence of big things that were eating other animals. The midden behaviour is particularly promising, and it does explain why we don't find broken plates. Whatever it was eating the carpoids, it was clearly pretty dextrous in getting the juicy bits our of the skeletons...

    Architeuthoceras - thanks also. Your comment might have helped to solve another riddle. We have a site with exceptional preservation where there are very few arthropod remains. Live animals might have escaped, but moults..? Given that nautiloids are a major component of the fauna, this could explain it.

    The possble nautiloid midden is actually just a loose end in the paper - we're describing a new fauna with the oldest known sea cucumbers, and are trying to tie up as much of the ecology as we can get to grips with.
     
  6. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    copies of papers are highly solicited :grin:
     
  7. acutipuerilis

    acutipuerilis Larval Mass Registered

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    I'm sure that can be arranged! (allowing for reviewers, of course...) :roll:
    We're trying Palaeontologia Electronica first, partly because it's open access, but will report back on progress. The more I look into the midden thing and the prey preference aspect, the better fit it seems to be... of course, whether Ordovician nautiloids did anything remotely similar is another matter entirely!
    Thanks again,
    Joe
     
  8. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    Fun Stuff! I thought the midden sounded similar to what you are finding as well as the liquification of the internal parts. I wonder how poisonous our Ordovician nautiloid friends would have been both in their bite and as a food. All cephs today are considered to have some kind of poison that they use to kill/paralyze their prey. From what I have read, most (but there are others that harbor bacteria rather than create their own) of these kind of poisons originated as normal biological secretions for digestion that evolved into an additional use in concentrated form.
     
  9. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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  10. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

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    Congratulations on the paper Joe, a nice read! :smile: It's nice to be a part of TONMO and I'm glad we could help a little. :grin:
     
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  11. acutipuerilis

    acutipuerilis Larval Mass Registered

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    Got there before me...

    I was just about to post a link - glad you found it first. :smile:
    Thanks again for all your help on this - it did make a real difference.
    Joe
     
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