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Novice needs evaluation of article on Dendrogramma

  1. Dec 30, 2014 #1
    Could people with expertise in the relevant field(s) please tell me what you think of the contents of the following article, with a focus on the suggestion that it could lead us to redraw the web of life:

    http://en.wikipedia.org/wiki/Dendrogramma

    Many thanks for all replies.
     
  2. jcsd
  3. Dec 30, 2014 #2

    jim mcnamara

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    A new phylum would be really unusual. So I doubt that will happen. What will have to happen is that genomic studies need to be done before someone decides to make that step. DNA gets fudged up in specimens that are preserved in formaldehyde, so the existing ones are not much help in that direction.

    Example of formalin and DNA on DNA analysis:
    http://www.researchgate.net/post/Any_advice_for_doing_PCR_on_DNA_from_samples_that_were_preserved_with_formaldehyde [Broken]
     
    Last edited by a moderator: May 7, 2017
  4. Dec 30, 2014 #3
    Jim,

    What I find noteworthy is that the same field researchers were unable to find any other specimens on their return to the site. The Wikipedia article doesn't say how many times they returned in the past 28 years, but the fact that it has been 28 years suggests they must have tried multiple times. Now that they have finally published, likely other field researchers will try. Even if no one ever finds any Dendrogramma again, however, the fact that they spent nearly three decades verifying their findings prior to publication gives them a lot of credibility. I'm far from an expert on the history of science, but this isn't the kind of thing I've ever heard of before. Have you?
     
  5. Dec 30, 2014 #4

    jim mcnamara

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    The level of ignorance we have regarding the ocean depths, particularly benthic organisms is amazing. The diversity down there is mind boggling and we have explored less than 5%. If some scientist from Mars sampled 5% the Earth's land area for terrestrial biota, in the essentially "blind grab" way we sample the oceans, the likelihood is they would not encounter humans in their sampling. Why? For one, large parts of the Arctic and Antarctica are uninhabited by humans. Another example in the US: There are vast areas in New Mexico and Montana that have nobody there. Literally. A few times a year some hardy soul may decide to hike or hunt somewhere in there.

    http://oceanservice.noaa.gov/facts/exploration.html

    Not finding something is hardly a big deal in this case. Period. Especially since they are trashing the area by dredging. If Dendrogramma requires a special environment they may have wrecked it with the sampling method, so our little beastie lives somewhere else now.

    Also consider: Schizaea pusilla, the curly grass fern, is found in the New Jersey Pine Barrens in a few places. Nova Scotia is the next closest location for the fern. Our little buddy may be really particular like the curly grass fern. Or have small pockets of limited numbers of individuals.
     
  6. Dec 30, 2014 #5
    I remember reading another article about an aquatic organism that has never been directly observed, let alone had someone collect a specimen of it. All they've found is burrows that analysis shows must have been created by something alive rather than non-biological processes. So, yeah, the deep ocean is a major frontier for research.

    This puts an interesting spin on the search for evidence of life on Mars. That's not being done randomly, as there are plans to send landers to what were, billions of years ago, river deltas with liquid water rivers flowing through them. Such missions had to wait until orbital observation of Mars had roughly mapped out the past history of the planet and identified such geological features. I'm looking forward to what the landers find in those former river deltas.
     
  7. Dec 30, 2014 #6

    Evo

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    Staff: Mentor

    This is not an acceptable way to start a thread. You need to do research of acceptable studies, then if there is something specific you do not understand, then you can ask for clarification on that specific question. Please put some effort into your questions.

    Thank you.
     
  8. Jan 1, 2015 #7
    As I [not expert, but a layman interested in astrobiology] remember it, the conclusion is that they need fresh specimens, for better ID and for sequencing. And the suggested placement will not "redraw" the topology of the standard tree much, it inserts a stem lineage at the root of Metazoa.

    Meanwhile, their suggestion is not bad though the specimen condition is. The fractal branching seen in the circulatory/digestive system (if that is what it is) could be an intermediate between the fractal branching rangiomorphs and the later gliding symmetries of metazoans like Spriggina. (The bodyplan-less Ctenophora and Porifera would also branch before Spriggina, in that order, obviously.) That could, excitingly, suggest that the still unplaced rangiomorphs are members of Metazoa, another small insertion and not a topological upheaval of "redrawing" the standard phylogeny.
     
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