# Talk:Cnidaria

The second paragraph says there are two cell layers, surrounding a non-cellular jelly.  However, the table in the "Distinguishing features" section says there are three layers.  Which is correct?  It can't be both.
Pstemari (talk) 02:49, 31 August 2020 (UTC)

Number of cell layers requires clarification. It makes sense to me if the author is referring to cell layers during very early development, but it doesn't refer to that anywhere. What am I missing?

Cnidarians have two main, continuous layers (the epidermis of both the interior and exterior of the body). The jelly-like layer in between is acellular. However, they also have organs in that jelly-like layer (muscle and nerve fibers), so some scholars describe them as triploblastic (three-layered). This is explained in the article. (The jelly also contains amoeboid cells that have both immune and regenerative function.) IAmNitpicking (talk) 19:15, 20 September 2021 (UTC)

The article mentions that cnids can regrow after fragmentation. Would each new cnid be considered a clone of the original cnid? Razor Rozar7 (talk) 22:54, 1 December 2008 (UTC)

Genetically, yes. But in the context of reproduction, cloning is a normal activity rather recovery after a disaster. --Philcha (talk) 23:38, 1 December 2008 (UTC)
So they are technically clones in that each is genetically identical to the original, but they aren't really considered clones? Razor Rozar7 (talk) 00:48, 4 December 2008 (UTC)
I think it's more a peculiarity of the English language - the noun "clones" refers to individuals that are genetically identical (and probably implies "produced asexually", as opposed to "identical twins"), and therefore includes regenerated fragments; but "cloning" (gerund of the verb), when used of a natural rather than lab process, refers to a normal activity rather recovery after an extermally-inflicted disaster. --Philcha (talk) 01:17, 4 December 2008 (UTC)

The Reagan era link leads to a disambiguation that discusses only the surname Reagan.  Does an appropriate article for the biological era exist, or is this entire sentence vandalism?

I've played around with trying to clarify the classification of subphyla and classes. I also added links to the source for the classification I used in the taxobox. The problem, of course, is that there are alternative classification schemes. As I am not a worker in the field, I have no feel for what best represents the current state of knowledge. I do feel however, that whatever classification scheme is used in the taxobox should be tied to a source. So, any dissenters to what I've done? -- Donald Albury 12:13, 10 July 2007 (UTC)

some one is vandalising the page repeatedly!!Silverpal 16:25, 21 September 2007 (UTC)

they  allhave stinging cells. more complex than sponges  —Preceding unsigned comment added by 67.168.221.157 (talk) 22:56, 29 April 2008 (UTC) 

The basic body shape of a cnidarian consists of a sac containing a gastrovascular cavity with a single opening that functions as both mouth and anus known as a manus.
I've looked for this term elsewhere and have found no reference to it. It is not used in any invertebrate zoology texts that I've found. Vandalism? --JimmyButler (talk) 15:05, 13 May 2008 (UTC)
Corrected ... wow this page is heavily vandalized with very immature edits. Guess it's those school kids doing projects in biology classes.--JimmyButler (talk) 15:20, 13 May 2008 (UTC)

The reference section is not actually considered "references" if they are not sourced within the document. Other than "additional reading" it serves no purpose. Adding a list of stately resources at the end and calling them references does not contribute to the confidence level or the accuracy of the document unless you can determine "what" and "where". That said, several of the references upon, reading, had excellent information that could be included and cited in the article.
I recommend renaming the reference section to Additional Resources or some such nonsense and merging the journal section with it. Then rename the Notes section to "references" which actually have embedded links between the document and the referenced source. Then going through and actually citing the information. 
In reality the very long "reading list" should be edited down to those most relevant or useful and the others deleted. People come to Wikipedia for the answer --- not as a hub for an infinite number of links elsewhere. 
If no one is opposed, I might dork around with it. I picked up a few skills while being beat up over the Introduction to Evolution FA concerning citations formatting and encyclopedic prose that can help a little here. I'll proceed with care .... don't want to be a Manus about it.--JimmyButler (talk) 01:07, 24 May 2008 (UTC)

Philcha, this sentence from the lead is grammatically incorrect: "Their distinguishing feature is cnidocytes...". 
"Cnidocytes" is a plural word, hence the statement should read "Their distinguishing features are cnidocytes...". However the syntax here implies that cnidocytes are not the only distinguishing feature(s). That's why I changed the text to "They are characterized by cnidocytes..." with the edit summary "Awkward singular/plural conflict changed". Axl ¤ [Talk] 06:45, 18 January 2009 (UTC)

We may have a dialect difference here. "Their distinguishing features are ..." leads me to expect something else as well as cnidocytes, but AFAIK cnidarians have no other features that are unique to them and possessed by all of them. As I said in the edit comment, "distinguishing feature" is plain language for "synapomorphy". --Philcha (talk) 08:57, 18 January 2009 (UTC)--Philcha (talk)
You have completely missed my point. I agree with your second sentence (as I commented above), which is why that is not what I recommended. As I said, both in my edit summary and my comment above, the problem lies with the mixed use of singular and plural forms in the sentence. Axl ¤ [Talk] 10:27, 18 January 2009 (UTC)
Re "the mixed use of singular and plural forms in the sentence", that could be resolved by "... is the possession of cnidocytes, ...", but I think the cure would be no better than the disease, because of the extra verbiage. --Philcha (talk)
Indeed I was considering "... the presence of cnidocytes...". ;-) While the phrase is longer, it is grammatically correct. Axl ¤ [Talk] 13:15, 18 January 2009 (UTC)

Congratulations on the GA for Cnidaria. This article generated some interest for me as well as my students a year ago in that a statement concerning Manus (mouth anus system) had languished there for some time. The need to correct this rather humorous factoid is what broke my self imposed Wiki-bann. It is such a delight to see the article tranformed so dramatically. Especially since the topic is probably high volume for high school students doing research on animal phyla. The before and after snap shot on this one speaks volumes about the work invested. Thank you. --JimmyButler (talk) 03:18, 27 January 2009 (UTC)

"An idiom is a phrase where the words together have a meaning that is different from the dictionary definitions of the individual words, which can make idioms hard for ESL students and learners to understand." ummm .... Conversely? But your right .... in the scheme of the transformation that took place here it is a non-issue! Cheers--JimmyButler (talk) 03:30, 27 January 2009 (UTC)

I just undid a change in number of species in lead from 9,000 to 11,000:

Not as shown in main text - see WP:LEAD.
No source given - see WP:V and WP:CITE.
Species counts are tricky. Those given in the article are based on formally-recognised species ("described" in the jargon) by class (jellyfish, anemones, etc.) To replace the count in the lead you'd have to find a source that gave other counts by class - one source, as summing counts of different classes by different authors would be like adding apples and oranges. --Philcha (talk) 13:24, 25 June 2009 (UTC)

I'm inserting a request on the talk pages for Ctenophore and Cnidaria to add an Etymology section.  The "silent c" is uncommon enough in language that I'd be very interested to know where it comes from.174.46.172.13 (talk) 09:30, 19 August 2009 (UTC)

I've added a link at the bottom of the page to the Wiktionary entry for Cnidaria, which indicates that it is derived from the Ancient Greek word for 'nettle'. -- Donald Albury 10:13, 19 August 2009 (UTC)
See Cnidaria#Cnidocytes. --Philcha (talk) 11:38, 19 August 2009 (UTC)

According to the Taxonomicon Cnideria [1]is a phylum with Anthozoa and Medusazoa as subphyla. So why is Medusazoa redirected to Cnideria. Perhaps discussion particular to medusazoans should be removed and included in a separate article for that group.
J.H.McDonnell (talk) 22:45, 18 October 2009 (UTC)

I agree that Medusozoa should have its own article rather than being redirected to Cnidaria. However material shoudl not be removed from Cnidaria, as this article is meant to be an overview of the whole phylum. --Philcha (talk) 06:12, 19 October 2009 (UTC)

Is this actually correct or just "for deh lolz"?
--68.158.0.237 (talk) 16:41, 1 November 2009 (UTC)

It's for real, from a good source that counts only confirmed species rather than estimates - see details at Cnidaria#Classification. --Philcha (talk) 18:16, 1 November 2009 (UTC)

"cnidarians, although considered more "primitive" than bilaterians, have a wider range of genes, and that bilaterians have introduced few new genes and that most have lost several—this reduction is most striking among the ecdysozoan group of protostomes, which includes arthropods and nematodes.[44] In fact cnidarians, and especially anthozoans (sea anemones and corals), retain some genes that are present in bacteria, protists, plants and fungi but not in bilaterians."
Use of "although" seems to imply that what follows contradicts the idea of cnidarians being more primitive than bilaterians. But anything found in "bacteria, protists, plants and fungi but not in bilaterians" is most certainly a primitive trait (=found in common ancestor though perhaps lost in some descendants) for animals. I understand the intent here -- that some people think of "primitive" as "more simple/crude" -- but I think this rather adds confusion than clarifies, by somewhat confusing the biological definition of primitive (primitive characters = those found in common ancestor, as opposed to derived characters) with the colloquial meaning. I think simply removing the clause "although considered more 'primitive' than bilaterians" would be best. Vultur (talk) 09:00, 25 January 2010 (UTC)

IIRC the pattern in which primitive organism have more wider range of genes than their derived descendants is quite common, and this point should therefore be retained. How about e.g. "cnidarians are considered more primitive than bilaterians but have a wider range of genes, while bilaterians have introduced few new genes and most have lost several—this reduction is most striking among the ecdysozoan group of protostomes, which includes arthropods and nematodes.[44] In fact cnidarians, and especially anthozoans (sea anemones and corals), retain some genes that are present in bacteria, protists, plants and fungi but not in bilaterians." --Philcha (talk) 10:51, 25 January 2010 (UTC)
The statement that "bilaterians have introduced few new genes" seems highly misleading.  Genes (in the sense of protein-coding sequences) don't come from nowhere (at least this would be exceptionally rare), so any modern gene derives from some ancestral gene -- but bilaterians have millions of genes that are not found in other organisms.  Maybe a less misleading statement would be that bilaterians have lost more ancestral genes than cnidarians have? Looie496 (talk) 17:35, 25 January 2010 (UTC)
"In fact cnidarians, and especially anthozoans (sea anemones and corals), retain some genes that are present in bacteria, protists, plants and fungi but not in bilaterians" is based on ref [45] and looks very solid.
The first sentence, "cnidarians are considered more primitive than bilaterians but have a wider range of genes, while bilaterians have introduced few new genes and most have lost several ..." is based on ref [44], but that surveyed one family genes. I'll check this outside in more detail today, when I'll now at home and can use my main computer. --Philcha (talk) 21:59, 25 January 2010 (UTC)
I agree that the sentence based on ref 45 is okay, the issue is with the other one.  It's really a question of what counts as a "new gene".  Since no gene remains fully invariant over time, and every gene derives from some ancestor, no gene is ever either purely new or purely old, so there is bound to be some arbitrariness about this. With the current wording, I don't think many readers will understand the sentence correctly.  Regards, Looie496 (talk) 22:39, 25 January 2010 (UTC)
A slightly fascinated, but not unrelated aside. The issue of it being not uncommon for earlier lifeforms to have a wider range of genes than their descendants appears to be consistent with Stephen Jay Gould's argument pertaining to reduction in disparity as measured by both the lack of new "body plans" over time and the lack of any major modifications of old ones.
On the evolution of new gene variants, I wouldn't have thought this was particularly controversial. It would come down to how a new gene is defined. I guess that this varies in the literature, with some focusing more on the gene structure, and some more on the function. And I guess it's easier to see this in literature on organisms where it's easiest to study phylogenetic change. Such as those with short lifespans and rapid replication, like micro-organisms and good old Drosophila melanogaster. Just a loose hypothesis on my part for comment if you see fit (doesn't matter if you don't, if I'm around long enough, I'll check it out myself, having created a question for myself). Wotnow (talk) 08:52, 26 January 2010 (UTC)

I tend to write long, multi-clause sentences myself, but I found the following sentence hard to follow, and had to read it several times to be sure I understood it:

Cnidarians are classified into four main groups: sessile Anthozoa (sea anemones (not sessile but only move 3-4 inches an hour), corals, and sea pens); swimming Scyphozoa (jellyfish); Cubozoa (box jellies); and Hydrozoa, a diverse group that includes all the freshwater cnidarians as well as many marine forms, and has both sessile members such as Hydra and colonial swimmers such as the Portuguese Man o' War.
Basically, it looks like two of the groups are identified as "sessile" and "swimming", and then the scheme shifts to using orders. There are too many asides, as well. There is a shorter and simpler version of this sentence in the "Classification" section. Neither the sentence in the lede nor the one in the "Classification" section agrees with the classification in the taxobox. The lede should be a summary of the article. I'm not sure that the classification of members of Cnidaria needs to be included. A simple list of some easily recognizable members (i.e. anemones, corals, sea pens, and jellyfish) should be sufficient for the lede. -- Donald Albury 11:41, 28 March 2011 (UTC)

Hi, Donald Albury. That para is about classification, not locomotion. I've edited to "the almost wholly  sessile Anthozoa (sea anemones, corals, sea pens); swimming Scyphozoa (jellyfish); Cubozoa (box jellies); and Hydrozoa, a diverse group that includes all the freshwater cnidarians as well as many marine forms, and has both sessile members such as Hydra and colonial swimmers such as the Portuguese Man o' War." --Philcha (talk) 12:47, 6 April 2011 (UTC)
The taxobox has one view of the taxonomy. The Taxonomicon gives no citations, authors, etc., so by WP:V it's not a 1st-class source. It is more consistent with the cladogram at Cnidaria#Family_tree. But cladistics, and especially molecular phylogeny is turning up traditional taxonomy and this may make taxoboxes obsolete. --Philcha (talk) 12:47, 6 April 2011 (UTC)
I doubt taxoboxes are going away. Competing classifications are found in many articles about life forms, and we don't have a consistent way of presenting them, but infoboxes of all kinds seem to be firmly imbedded in WP culture. -- Donald Albury 12:58, 6 April 2011 (UTC)

"Cnidarians form an animal phylum that more complex than sponges, about as complex as ctenophores (comb jellies), and less complex than bilaterians"
An unclear sentence. It's written to say that the phylum is more complex, but appears to mean that the animals of the phylum are individually more complex.  — Preceding unsigned comment added by 144.118.94.176 (talk) 01:36, 5 December 2012 (UTC) 

After reading that section that was created again, polymorphism isn't specifically about zooid differentiation, which confused the topic by suggesting that colonial zooids were the same as medusa and polyp forms in all cnidarians. I reworked it a bit to be more clear. Esoxidtalk•contribs 22:04, 29 April 2014 (UTC)

Lately Myxozoa has been shown to be a Cnidarian (as can be seen on the Myxozoa page on Wikipedia), yet that is not discussed in the evolutionary history. Also - they are more likely closer to Medusozoa than Anthozoa, so they should be deep within the Cnidarian tree and not next to Bilateria at all (the whole bilaterian debacle was because of fish fragments in the Myxozoa DNA). I don't know how to edit Wikipedia well, so I think someone should change that.  — Preceding unsigned comment added by Erez87 (talk • contribs) 12:53, 6 June 2016 (UTC) 

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On this cladogram the placozoa are placed as siblings to the bilateria.  But other articles — Planulozoa, ParaHoxozoa, Diploblast — place placozoa as cousins to both Cnidaria and Bilateria. Can this discrepancy be explained in the article (or is one version less accepted)? — Henry chianski (talk) 20:50, 19 January 2018 (UTC)
The refs in this article are really dated and everything needs to be updated. Cnidaria is sister to placozoa or bilateria.Jmv2009 (talk) 18:09, 2 November 2018 (UTC)

An editor has asked for a discussion to address the redirect Acalephae. Please participate in the redirect discussion if you wish to do so.  – Arms & Hearts (talk) 13:52, 9 June 2019 (UTC)

The entire article from the second sentence is so technical and loaded with specialist jargon with no explanation, that it conveys almost nothing to me, a scientifically literate person.  It needs a major revamping, preferably by someone with not so much expertise that they can't explain things in plainer language.  Zaslav (talk) 19:57, 24 March 2020 (UTC)

There is an article about Cnidaria written in simple English.--SharʿabSalam▼ (talk) 20:05, 24 March 2020 (UTC)

I have moved the following question about the mesoglea (which was added to the article by an IP) to here: "* (attn: how can this be termed "non-living" when it contains nerve bundles, muscles and amoeba that function as an immune system)?)" - Donald Albury 11:51, 28 March 2020 (UTC)

Note to @Spaully: actually there are large planktonic organisms. Your edit is correct, because cnidarians are not limited to eating small plankton, but your comment contains a misconception. Wikipedia's own plankton article says, "Though many planktonic species are microscopic in size, plankton includes organisms over a wide range of sizes, including large organisms such as jellyfish." IAmNitpicking (talk) 18:28, 24 July 2020 (UTC)

Thanks, yes the revert did lead me to read about larger plankton species and realise my error. Apt name by the way! |→ Spaully ~talk~  21:14, 25 July 2020 (UTC)

@Apokryltaros edited the page to state that myxozoans are unicellular. They are not. See, e. g. https://www.researchgate.net/publication/282249669_Myxozoa. They have few cells, but more than one. IAmNitpicking (talk) 21:24, 25 April 2021 (UTC)

On the other hand, they are not polyps, either.--Mr Fink (talk) 02:04, 26 April 2021 (UTC)
I agree, of course. Note at least one paper places them in Bilateria! https://academic.oup.com/mbe/article/27/12/2733/1071669
A couple of papers I found imply that the adult myxozoan represents a highly modified medusa. I can find no source claiming they are polyps. IAmNitpicking (talk) 02:40, 26 April 2021 (UTC)

How is phylum Cnidaria set to phylum petalonamae? An extinct clade? 76.144.49.221 (talk) 13:27, 24 December 2022 (UTC)

In § Polymorphism, the sentence below gives an example that could identify the different types of individuals more clearly: 
"For example, in Obelia there are feeding individuals, the gastrozooids; the individuals capable of asexual reproduction only, the gonozooids, blastostyles and free-living or sexually reproducing individuals, the medusae."
I can't tell, for instance, whether a blastostyle is one of the kinds of "individuals capable of asexual reproduction only", or not.  A subject matter expert may know; but I'm left guessing. yoyo (talk) 06:14, 15 August 2024 (UTC)

I'm not an expert, but in Gonophore, "blastostyle" is defined as a structure holding a "gonophore", a reproductive organ that produces gametes. In some cases gonophores develop into medusae. That doesn't necessarily make the sentence clearer, but I think it is safe to say that blastostyles are not "individuals", although gonophores may develop into individuals. Donald Albury 16:41, 15 August 2024 (UTC)