Lepidoteuthis - with scales.

Discussion in 'Lepidoteuthidae' started by Phil, Jul 30, 2003.

  1. Phil

    Phil Colossal Squid Supporter Registered

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    The old 1896 woodcut I have just bought (photo on the Antique Ceph Print thread) mentions on the reverse an unusual squid covered in scales known as Lepidoteuthis. I was not aware that any squid had such a feature. I have looked up this animal on the Tree of Life project and there are indeed some interesting photos that confirm this.

    I was wondering what exactly is the function of these scales or 'dermal cushions' as they are referred to, as this is such an unusual feature?

    Photos here, if anyone would like to take a look:

    Lepidoteuthis Tree of Life page
     
  2. Steve O'Shea

    Steve O'Shea Colossal Squid Supporter

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    Phil, there's a rather interesting paper due out in August that deals with Lepidoteuthis .... very interesting that you should bring this, of all genera up at this point in time. Another genus with scales/dermal cushions is Pholidoteuthis, and we're in the midst of preparing a paper on this genus also.

    Both Pholidoteuthis and Lepidoteuthis used to be placed in the family Lepidoteuthidae, but Pholidoteuthis was separated out some years back and is now in its own family, the Pholidoteuthidae.

    The scales could have several functions. Lepidoteuthis is quite closely related to species in the Octopoteuthidae (Octopoteuthis and Taningia)..... another family of squids that we're working away on (have several specimens of a giant Octopoteuthis to try and name, and a few other quite confused species to tag names to ... but the group is really quite complex and the systematics in disarray). More to follow, some soon, a little in a few months.
    O
     
  3. Phil

    Phil Colossal Squid Supporter Registered

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    As a bit of a historical aside, Lepidoteuthis appears to have a quite interesting story concerning its discovery. It was actually discovered on a ocean-going expedition by the Crown Prince of Monaco Albert Grimaldi (Albert I) (1848-1922) and was named by a naturalist companion in his honour, literally ‘scaly Grimaldi squid’.

    Despite being a veteran of the Franco-Prussian war and heir to the throne, Albert was apparently an accomplished mariner and oceanographer, mapped the gulf stream and commissioned a map of the seafloor in the Atlantic. He collected thousands of marine specimens and made surveys of plankton in the Atlantic. He even had a series of four large steam yachts built for the purposes of marine research! Albert dissected the first recorded Lepidoteuthis after seeing it vomited from a sperm whale stomach. Another squid was named after him was caught in the Azores in 1898 called Grimalditeuthis. It’s a pity that the travels of this ocean-going royal personage came to an end with the outbreak of World War I, he was too sick to continue his explorations in 1918.

    It’s hard to imagine a modern Royal engaged in scientific research these days. I can’t really see the Queen of England poking around a sperm whale stomach contents or hauling in a deep water trawl net. Pity.
     
  4. Steve O'Shea

    Steve O'Shea Colossal Squid Supporter

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    ...a great pity indeed. They seem more concerned with polo than deep-sea exploration; with all of that money they could fund some pretty spectacular expeditions.

    Perhaps I should invite Queeny along?
     
  5. Fujisawas Sake

    Fujisawas Sake Larger Pacific Striped Octopus Supporter Registered

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    Cool.

    So here's my two cent question: why the scales? I wonder if they're an evolutionary throwback, i.e. "reverse-evolution" (I hate that term too, but I can't think of any better ones right now) point mutations along Hox genes? Or are they some kind of adaptation, like a mutant variety of skin cell?

    Sorry about the "throwback" remark, but I still think that there's some ancient mollusc link that still might be encoded in deep time DNA.... Some link to the past and where exactly they came from.

    Oh well.

    Anyway, this post is related to an earlier post on the Fossils and History section. I wrote something under "New Article on the Cephalopod Page" about the evolutionary theories behind molluscs (at least the ones with which I'm familiar) and I wonder if the scales might have to do with the evolutionary history of cephs?

    Sushi and Sake,

    John
     
  6. Steve O'Shea

    Steve O'Shea Colossal Squid Supporter

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    Funny that you should raise that question today John - I was reading up on the exact subject matter this afternoon. ..... Morrow I'll transcribe the theory advocated by Roper & Lu, a few years ago now, in a comparative study of dermal scales in a few genera (Lepidoteuthis, Pholidoteuthis ... could have been more).

    As an aside, for a future discussion, here's a term for you: atavism. What do you make of this?

    Back to the subject at hand though, we're working on both Lepidoteuthis and Pholidoteuthis at present (and this rather bizarre, possible synonym, Tetronychoteuthis .... although I'm not entirely convinced); only Lepidoteuthis has the 'real' scales. Keep your eyes on the JMBA website for an upcoming article/August release ..... it will help explain a few things. Tony has a sneak advance copy, so the minute it's out we'll have it online here anyway.
    Cheers
    O
     
  7. myopsida

    myopsida Vampyroteuthis Supporter

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    Emperor Akihito of Japan has published extensively on pufferfish taxonomy (Fam. Tetraodontidae). But since he got the job full-time he's been otherwise preoccupied with other things.
     
  8. Fujisawas Sake

    Fujisawas Sake Larger Pacific Striped Octopus Supporter Registered

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    :heee: Point well taken.

    That's a tough one. See, I think that there is a possibility, however remote, that ancestral traits "lost" along the evolutionary path are still encoded in DNA. albeit sleeping between relatively recent STOP and START codons. There is a lot of so-called "junk" DNA in our systems that many scientists believe is the sloppy work of viruses trying to get a foothold in our cells. Then there are small, quiet mutations, etc. that can occur. Its a mess, but probable.

    My take is that maybe the scales may be an atavistic expression of earlier model teuthoids or their molluscan ancestors, brought to the surface and recombined with current features. Or maybe, they are further proof that the squid is the molluscan raptorial "fish" form.

    Just what are the scales used for anyway?

    John
     
  9. Steve O'Shea

    Steve O'Shea Colossal Squid Supporter

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    I'll probably have to correct this post tomorrow coz I'm indulging in a much-needed :wine:

    I recall reading that the scales were actually vacuolated (some neat SEM shots), and the theory advocated by Roper & Lu was that these vacuoles were full of ammonium ions, thus rendering the animal neutrally buoyant in the water column. Now I could be totally up the creek ( :boat: ) in a little canoe, as Kat is as we type, but I'll check it out again tomorrow and post away.

    The atavism comes in later .... watch this space
    O
     
  10. Steve O'Shea

    Steve O'Shea Colossal Squid Supporter

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    What's his new job that keeps him from his science? :jester: I mean, like what does an emperor do all day? Oooops, too much :wine:

    Toodles, O
     
  11. myopsida

    myopsida Vampyroteuthis Supporter

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    Looks for his new clothes?
     
  12. Fujisawas Sake

    Fujisawas Sake Larger Pacific Striped Octopus Supporter Registered

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    The ammonium vacuoles would make sense as a buoyancy adaptation, although its eerily looking more and more fishlike. What's next, swim bladders? Gee... :heee:

    Why wouldn't they just retain the ions in their flesh? And is this the case across the entire Pholido- and Lepidoteuthidae families?

    Heh heh... These body plans just get weirder and weirder. If in the future I'm sitting on a tropical beach somewhere, and some scaled octo comes out of the surf, slides up to me to ask me for some raspberry sake, I'm quitting! :lol:

    Sushi and no sake for octo!

    John
     
  13. Steve O'Shea

    Steve O'Shea Colossal Squid Supporter

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    There is an octopus with a 'swim bladder' - a very bizarre arrangement. It is found in the female of Ocythoe tuberculata, but I'm not sure if the male also possesses this structure (the female is considerably larger than the male); family Ocythoidae, monotypic.

    I've only ever dissected one mature female (they're quite scarce); they also brood embryos in their distal oviducts - another very bizarre attribute for a cephalopod.

    I agree with you John that they might as well distribute ammonium ions throughout the body tissues if achieving buoyancy was the sole purpose of these scale-like structures in the Lepidoteuthidae and Pholidoteuthidae. Lepidoteuthid squid are way-cool (and very rare, at least in collections) squid!!!
    Cheers
    O
     
  14. Phil

    Phil Colossal Squid Supporter Registered

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    Steve, I know this is not my section so I hope you don't mind me posting this, but I could not resist!

    I've just looked Ocythoe up on the Tree of Life Pages, there is a nice diagram of the swim bladder here:

    Ocythoe Swim Bladder

    It does appear, from this site, that this structure is only present in the females. This species displays extreme sexual dimorphism with the male at about 30mm being about a tenth the length of the female. It also mentions that Ocythoidae are the only octopus family that bear live young, with the juveniles hatching in the oviducts. Is this truely a unique approach amongst the cephalopods, or are there others?

    The male has also been known to hide inside the bodies of salps (free swimming sea squirts), leaving the protection when approached and retreating when the threat has passed! (Source here: Mark Norman's Cephalopods: a World Guide).

    It really is quite astounding the sheer diversity of body plans and differing functional mechanisms within the cephalopods. So many different approaches to the same problems, and so many resolutions.
     
  15. Phil

    Phil Colossal Squid Supporter Registered

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    Hope you don't mind me risking sidetracking this interesting discussion about Lepidoteuthis, but I once saw a fascinating TV documentary that demonstrated your point, John. I am not exactly sure how it was done but a certain section of DNA coding was chemically 'switched off' somehow in an embryonic chick. The section that was turned off controlled the formation of the beak. When the chick was X-rayed a few days later it seems that instead of a beak fully forming, rudimentary teeth began to develop along the jaw. The idea here was to demonstrate the dinosaur/bird link and that 'fallback' structures are indeed encoded in DNA. Atavism indeed!

    I freely admit I do not understand genetics in any detail. Would the sequence of genes that caused the teeth to form been a recessive trait?

    You might like to look this up, the experiment was three or four years ago. Anyway, back to the squid........
     
  16. Steve O'Shea

    Steve O'Shea Colossal Squid Supporter

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    ..... a fascinating and relevant digression Phil!

    Wouldn't it be so nice to be able to grow these squid from the eggs, then subject them to all manner of environmental or genetic perturbations ....

    I know I run the risk of further hate mail by making suggestions like these, but if you can manipulate chick embryonic development to the extent these ancestral characters/states appear, then just imagine what you could do with ..... Spirula for instance. Would an ammonite develop? Or what would become of Vampyroteuthis? Cirrates also .... what ancestral characters/states would appear????

    These are exciting, but at the same time ethically challenging times.

    Why does one octopod only retain a swim bladder .... or is it a derived state? Perhaps we should experiment with the likes of Ocythoe. Perhaps I'd best get back to work and figure out how to keep these animals alive, happily, in containment.
    Cheers
    O
     
  17. Fujisawas Sake

    Fujisawas Sake Larger Pacific Striped Octopus Supporter Registered

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    Steve and Phil,

    Whoa, we are REALY getting off topic here :) . But, since we are... As far as the traits being recessive or dominant I have no idea. But, expression of a trait is based upon whether a gene is dominant and its overall frequency within a given population. And, there cannot be a suppressing factor involved.

    As far as how you shut down and turn on gene sequences, its all dependent on activation of regions of DNA called "start" and "stop" codons. These are regions that tell enzymes where to begin and end reading and coding information. Kinda like regions of information on a hard drive, except you don't have to defrag it! :lol:

    Mind you, genes also can be linked, meaning that one gene affects the expression of another or more. Also, there is incomplete dominance and co-dominace. And mutation... Wow.

    Yeah... Its a mess.

    A few years ago PBS ran an episode of "NOVA" called "The Real Jurassic Park", where they discussed the concept of essentially "reverse-engineering" dinosaurs from birds on a genetic level over several generations. Interesting theory, albiet a weird one. Evolution is supposed to be a one-way process for a reason, given mutation, gene frequency, and directional selection.

    Steve, I know what you mean. The real issue here is not whether or not we can reverse enigineer a ceph but rather how we do it. It would involve EXTENSIVE gene mapping, and a high degree of work over several ceph generations. And in the end, would it realy be an ammonite, or some mutant mixture of man-made animal?

    Troubling times indeed.

    So, on a more light note, about the swim bladders: Its still not a ceph asking me for raspberry sake, so I'm safe! Dude, what's next, a pulmonate ceph? (Really stretching for that squibbon) :mrgreen:

    Sushi and Sake,

    John
     
  18. Fujisawas Sake

    Fujisawas Sake Larger Pacific Striped Octopus Supporter Registered

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    My wife just asked me a good question to post... Has there been any work on gene-mapping in cephs?
     
  19. Steve O'Shea

    Steve O'Shea Colossal Squid Supporter

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    ..... will respond soon - just a complicated question. In brief, yes, but I need to speak to a colleague in order to get the references (there is some very interesting work being done, but it goes well over my head) - I believe it is rather recent work.
    Cheers
    O
     
  20. Fujisawas Sake

    Fujisawas Sake Larger Pacific Striped Octopus Supporter Registered

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    Thanks Steve,

    I know gene-mapping is pretty hard-core work right now... And EXPENSIVE, so I would understand if few to none are working on Ceph genes. Its a nice thought though...

    John
     

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