Talk:Ctenophora

Phylogeny and lead section
- there is now a major mismatch between the Phylogeny section and the lead section. I see you have added new citations and other materials to the lead. Far from 'clarifying' the article, the phylogeny paragraphs in the lead are now contradictory, out of sequence, and contradictory, with no clear conclusion; the new materials are not summaries of anything in the body of the article, and are not present in the body. We should not have anything 'new' in the lead, and that basically means that we shouldn't have any citations there, barring citations repeated there from the body if anything is actually challenged. The situation right now is in urgent need of sorting out. Chiswick Chap (talk) 18:57, 6 October 2018 (UTC)
 * The reference in the lead is not new: it has been copy-pasted from the 'Evolutionary history' section. However, I agree that the match between 'Evolutionary history' and 'lead' sections might be better articulated. We should work on it, perhaps just mentioning in the lead that the phylogenetic positions of both sponges and ctenophores is the focus of debate, and then moving to the two main hypotheses. Manudouz (talk) 17:13, 7 October 2018 (UTC)
 * Well, I can't see any reason to have refs in the lead here, let alone additional ones. What we need is a unified cited text in the body of the article: if you'd like to do that, that'd be great. Once that's complete the lead can be rewritten as a summary of the body: I would be happy to do that at that stage. Chiswick Chap (talk) 17:52, 7 October 2018 (UTC)

For your consideration
I think it is better to discuss edits on the article's talk page instead of the users' talk pages, as it allows others to decide what is good sources or not.

I added new info and three new references a while ago. Whenever you add something from The National Center for Biotechnology Information (NCBI)/United States National Library of Medicine (NLM)/National Institutes of Health (NIH), I assume the source is good enough. And apparently, so does Wikipedia considering it doesn't ask for a captcha security check in these cases. The link (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5868061/) is about how chemicals released from other individuals of the same ctenophor species can affect egg production. The other two were from sciencemag.org and sciencealert.com: https://www.sciencealert.com/this-animal-s-butt-appears-when-needed-and-it-could-help-us-understand-how-ours-evolved and [https://www.sciencemag.org/news/2016/03/why-watching-comb-jellies-poop-has-stunned-evolutionary-biologists They're about growing a temporarily anus, as amazing as it may sounds.

But according to the user Zefr, none of these links are good enough, and he posted a message on my page where I was reprimanded for making "unconstructive edits", the last edit I made was reverted just a few minutes after being published. The way I see it, mere mortals trust scientific publications on the net as long as the webpages are trustworthy. So I leave it to others to draw their own conclusions. 84.208.233.159 (talk) 21:51, 31 December 2019 (UTC)
 * Comments: 1) your edit in October used wording such as "appears to be", "assumed to be", and "could be", indicating the primary nature of the research, and inability to state an encyclopedic conclusion (unfortunately used often in this article, as it must be in most cases, as the research conclusions are speculative); 2) the speculation in published research leads to potential for synthesis of tentative conclusions by encyclopedia editors, WP:SYNTH, which I felt was the case in your edit (it reads ok now); 3) PMID 29576018 - which you attribute to "The National Center for Biotechnology Information (NCBI)/United States National Library of Medicine (NLM)/National Institutes of Health (NIH)" is published by BioMed Central - the NCBI, PubMed, and NLM are providers of a publication listing service (not publishers themselves, in this case); 4) please use Citer to choose the correct reference template and fill out details for your sources. --Zefr (talk) 00:20, 1 January 2020 (UTC)
 * Nitpicking. When writing "appears to be" is simply a way of referring to new research that is not written in stone yet. The phylogenetic tree is adjusted all the time, so making it sound like all is clear and settled would not be right. Based on present knowledge, this is where we are today, but there is no guarantee this is where we are tomorrow. If articles about biology should wait to add information till all of it was confirmed once and for all, one would have to wait several years. The article should reflect that. But if the choice of words bothers you, then you are always free to do this little thing called editing, where you use your own words, instead of reverting the whole thing. The same goes for everything else.
 * The fact that some of the sources are "not good enough" because another editor says so, without any reference to Wikipedia rules or any other reasons, does not mean they are not correct. 92.220.125.90 (talk) 22:42, 2 May 2021 (UTC)

The external systematics problem
I find some issues with the following part of the lead, for two reasons.
 * Biologists proposed that ctenophores constitute the second-earliest branching animal lineage, with sponges being the sister-group to all other multicellular animals. Other biologists once believed that ctenophores were emerging earlier than the sponges, which themselves appeared before the split between cnidarians and bilaterians. However reanalysis of the data showed that the computer algorithms used for analysis were misled by the presence of specific ctenophore genes that were markedly different from those of other species. Molecular phylogenetics studies indicate that the common ancestor of modern ctenophores was cydippid-like, descending from various cydippids after the Cretaceous–Paleogene extinction event 66 million years ago. The most recent analysis suggests that comb jellies are older than sponges.


 * 1) The first problem I see is that "the latest split of the ancestors of the ctenophores and those other extant groups of animals" is identified with "the emergence of the ctenophores", and correspondingly for the sponges. Now, our article and some of the sources I've broused agree on the latest common ancestor of the extant ctenophores living considerably later than at the time of this split. IMHO, this means that for some hundreds of millions of years the animals ultimately giving rise to the extant ctenophores not immediately should be considered as ctenophores themselves.
 * 2) The second (and more important) problem concerns the description of the present consensus about the outer systematics of the ctenophores. The text expresses the Porifera-sister theory (i. e. that sponges be the sister-group of all other animals) as definitely the modern consensus, and the alternative Ctenophora-sister theory as mistaken and now abandoned. However, the last sentence obliquely refers to a rather recent article (Li et al.), summing up the earlier ones, and strongly supporting the Ctenophora-sister theory. Also disregarding this article, I believe that the matter could not be said to have lead to a consensus.

Of the articles cited in this part of the lead, and younger than ten years, the following support the Porifera-sister theory and

while the ctenophores were suggested as the sister group of the others in and as recently as in (However, I do not have access to Berwald's book. Moreover, I note that this book is not included among the 62 references to Li et al. while the other enumerated references are. This, together with the title of Berwald's book, make me guess that the placement of ctenophores or sponges as most far off from the cnidarians was neither a main issue and nor subjected to an independent analysis directly from data in that work. For these reasons, I just concidered on the other references.) Li et al. thoroughly discuss also other investigations; most of those later than 2015 proposed the Porifera-sister theory, but a few instead proposed the Ctenophora-sister theory.

My impression from browsing the four enumerated articles is that the issue is rather technical, and not primarily one of finding more data. Seemingly, more data gave a somewhat firmer support for the Ctenophora-sister theory, but mainly under "site-homogeneous" assumptions. In other words, in the simpler analysis, all amino acids in any given protein in these studies are assumed to have i.i.d. probability for mutating. Under one kind of competing "site-heterogeneous" assumptions, the Porifera-sister theory is preferred. However, Li et al.notes that also some other kinds of "site-heterogeneous" assumptions support the Ctenophora-sister theory.

Biologically, I believe that site-heterogeneity is the more reasonable assumption. However, since this assumption also leads to increased complexity of the calculations, the issue does not seem to be resolved. The fact that the latest re-evaluation article supports the Ctenophora-sister theory, while the majority of those for a couple of years earlier didn't, also indicates that we should describe the issue as "not resolved", I think. This should be reflected both in the lead and in later parts of the article. However, possibly we should describe the Porifera-sister theory as "the majority opinion".

If no-one else has an opinion about this in the next few days, I'll rewrite the part of the lead I cited supra. JoergenB (talk) 23:09, 18 January 2021 (UTC)

Very interesting, but lots of questions remain
I've read the article and found it very informative, but it leaves me wanting for more. The first suggestion I would like to make is to add Placozoa to the table "Comparison to other major animal groups". I will instantly agree with anyone who does not find the Placozoa a major animal group, but they are more basal animals then Bilatarians (and Cnidarians) and so are more interesting to compare with. Also Cnidocytes and Colloblasts should be removed, since they clearly only developed in the animal group that has them so are not relevant as a means to compare. What is an apical organ? Couldn't find a page that explains it.

The most interesting item in this list is the lack of microRNA in Ctenophora. As the page on microRNA states both plants and animals have them as an essential item. So either they go back a very, very long time or they have been invented in major groups independently (which is a highly unlikely option). Can somebody give the the latest common ground on that item? As sponges also have them, and the consensus is (and has been for >100y) that sponges evolved very early out of (colonial) Choanoflagellates and really went there own separate ways ever since, it is rather hard to imagine microRNA to have evolved 3 times over (in plants, in sponges en animals other then ctenophora). That could be a strong indication that the ctenophora could have split of even earlier then sponges (before micorRNA was invented in the line leading towards animals), but that would still leave the microRNA in plants unexplained. Do Choanoflagellates (or any other group of protists) have microRNA? Or is there really a great difference between (the biochemistry of) plant and animal microRNA and are they just grouped together for convenience as molecules that perform a certain task? If they have the same origin isn't it more likely that the ctenophora have lost them (and might that be a reason for their rather conservative way of live, as compared to f.i. the cnidarians with all those weird parasitic forms which have been around at least since the Cambrium)? Like I said, lots of questions and I hope there is somebody who has some answers.

Finely there seems to be a bit of a "who has the longest..." going on in the debate whether sponges or ctenophora branched of first. Surely some acadamic status is involved, but if ctenophora really split of even earlier then sponges, that would only mean that they, just like sponges, don't have much relevance for the main line of animal evolution, but are a just in their own separate sideshow. Codiv (talk) 18:00, 17 July 2022 (UTC)