Talk:Cnidocyte

  This article was the subject of a Wiki Education Foundation-supported course assignment, between 2 October 2019 and 14 December 2019. Further details are available on the course page. Student editor(s): Flora p7.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 17:53, 16 January 2022 (UTC)Reply

cnidocyte.gif and nematocyst.jpg have been removed because copyrighted. — Preceding unsigned comment added by N.hong.phuc (talk • contribs) 22:07, 21 March 2005‎ (UTC)Reply

That nematocyte image needs to be scaled down. As of now it stares people in the face, and that is not a good way to do it in a published encyclopedia unless you have seperate pages. And we don't have that here. The image is nice, just a bit large for Wikipedia. Spoiled Silk 15:13, 26 March 2007 (UTC)Reply

What is a cnydocyte -- a cell, an organism, a sub-cellular structure, a car? The article should introduce the subject with a definition or near-definition, and a few general sentences. There should be no section titled "General introduction": the text before the first section is the introduction. The article should stay on topic, connect the sentences, and explain related topics and their connection to the subject. The language and structure are needlessly complex; they should be simplified. -Pgan002 00:29, 4 August 2007 (UTC)Reply

I noticed that the problems were largely due to vandalism. I improved the page and remove the tags. -Pgan002 01:59, 4 August 2007 (UTC)Reply

The opening to this topic indicates that nematocysts are, like cnidoblasts (the proper term, cnidocyte is also used but not technically correct), cells. The nematocyst is not a cell, it is the extension of the cnidoblast cell membrane, making it an organelle. Integrated Principles of Zoology, Hickman, et al, probably any edition and year. mcnolan (talk) 17:50, 6 February 2008 (UTC)Reply

The article reads, concerning cnidoblasts: "It evolved in these aquatic animals as a means for them...". No structure evolves as a means for anything. The structure begins as some simple variation on a regular cell and the environment selects for it due to the advantage that the new variation gives the organism to survive and reproduce and pass on that variation. Cnidoblasts did not evolve SO the organisms could use them to feed. The cnidoblast evolved because each minor genetic change to the cell increased the organisms' ability to use the cellular organelle for catching food. No structure arises due to need. If the genetics are not there, there is no structure formed. mcnolan (talk) 17:58, 6 February 2008 (UTC)Reply

Why in the world would you title this article cnidocyte and then structure the article around that instead of nematocysts. My mind boggles at who thought this was a good idea. — Preceding unsigned comment added by 70.88.24.193 (talk) 14:16, 15 July 2011 (UTC)Reply

can be sourced from this article... i just dont know how

http://www.sciencedirect.com/science/article/pii/S0022098107003206 — Preceding unsigned comment added by 24.63.184.238 (talk) 08:14, 13 December 2011 (UTC)Reply

The sections in this article alternate between using "nematocyte/cyst" and "cnidocyte/cyst". Although either word is correct, and either will redirect to the page, it should probably be standardized for the sake of consistency. It's not a big deal, but if there's no difference I think it would be a welcome change. — Preceding unsigned comment added by 24.13.231.253 (talk) 03:53, 4 January 2012 (UTC)Reply

Under Structure and action-

“This discharge takes no more than a few microseconds, and is able to reach accelerations of about 40,000g.[1] Recent research suggests the process to occur as fast as 700 nanoseconds, thus reaching an acceleration of up to 5,410,000 g.[2] After penetration, the toxic content of the nematocyst is injected into the target organism.”

The consensus is that it takes approximately 3 milliseconds (3,000 microseconds) for most nematocysts to discharge, from trigger to full eversion of the entire tubule. The “recent research” that was cited was only an interpretation of the study by Underwater Times news service. While generally a good write-up, they did present an erroneous implication. The actual research paper clearly states that in the middle of the nematocyst discharge of one particular type (stenotele), there is an extremely quick stage where the stylets pierce the integument of prey. Certainly fascinating and more than worthy of discussion, but let’s not imply that the entire trigger to complete evagination process occurs in 700 nanoseconds at 5.4 million times the acceleration of gravity. The study also investigated the period up to stylet eversion which varied by up to 1.2 milliseconds, and the tubule eversion afterwards took many more hundreds of microseconds. (http://www.npr.org/documents/2006/may/jellyfish.pdf)

There is another growing consensus that the toxin delivered is not simply injected after eversion. The toxin is carried into the prey along the entire outside (previously inside) surface of the tubule. Also, at least in Chironex fleckeri, it is hypothesized that toxins are transmitted from the inside of the tubule along the length of the tubule to explain the fast reaction in humans via intra-capillary envenomation; however, the exact mechanism of this has yet to be described. Obviously, it is still possible that with millions of nematocyst intrusions, the tubule tips will occasionally terminate inside a capillary. There is much yet to be learned, and maybe an hypodermic needle analogy shouldn’t be presented as a resolved fact.

Under Discharge mechanism-

Likewise, while many researchers seem to have settled on the Calcium gradient hypothesis of osmotic pressure increase, even more recent research have proposed a proton gradient process for the first explosive step of discharge. This well written paragraph should include the fact that it is a hypothesis and not established science. (http://www.springerlink.com/content/773007561n7026t7/)

A diagram of the discharge mechanism of a nematocyst-

Beautiful drawing, very instructive. But, again I apologize for being picky, there are two problems. The first is that the barbs shown in the last image should be proximal to the body of the nematocyst, with the tubule everting beyond the barbs. The middle image properly shows the barbs ‘turning themselves inside out’, but it cannot then separate from the rest of the tubule and then reattach itself to the distal end of the tubule. For that barb to end up at the very end of the thread, it would have to be the last thing enverted, not the first.

The second problem is the description that appears when the thumbnail is clicked on-

“The middle image shows the open operculum, the rapidly uncoiling thread and the emerging barb. On the far right is the fully extended cell. The barbs at the end of the nematocyst are designed to stick into the polyp’s victim and inject a poisonous liquid. When subdued, the polyp’s tentacles move the prey toward its mouth and the nematocysts recoil back into their capsules.”

“A rapidly uncoiling thread” ignores the whole process of tubule evagination. And the nematocysts don’t “recoil back into their capsules”. After discharge, nematocysts are absorbed by the cnidarian and new nematoblasts must be created from interstitial stem cells (often at the base of the tentacle) and while differentiating into new nematocysts they also travel down the tentacle between epithelial layers to their final destination (in species specific patterns) within the ectoderm. This is not only an amazing process, but provides an explanation for the often complex triggering mechanisms that befits this ‘expensive’ resource of cnidarians. Gseymour (talk) 17:11, 3 May 2012 (UTC)Reply

Be bold and feel free to make the edits! - M0rphzone (talk) 02:09, 20 March 2013 (UTC)Reply

Let me preface my comments by saying that Wikipedia is a place for facts, not a place for sensationalizing a subject. To repeat any type of hype, even from scientists hungry for funding, devalues its worth as a trusted place for truthful information. It should not compete with newspapers, magazines, or any other journalistic efforts to attract attention. In that vein, allow me to take issue with some information under the heading of:

Nematocyst toxicology- “It [Chironex fleckeri] causes excruciating pain to humans, often followed by death, sometimes within two or three minutes. The chance of survival if stung while swimming alone is "virtually zero."

While excruciatingly painful and one of the quickest acting venoms known, it neither ‘is often followed by death’ nor does it guarantee death if stung while swimming alone. The facts are that this particular species, Chironex fleckeri, has caused 70 recorded fatalities in the last 128 years in Australia, which certainly justifies great effort and expense to ameliorate its danger to humans, yet hardly justifies any exaggeration of its lethality. From 50 to 200 C. fleckeri stings are reported each year in Australia, with one fatality every two years on average. It is reasonable to assume that the actual number may be considerably higher than the recorded number of stings.

PJ Fenner conducted a study in Australia of C. fleckeri sting victims and concluded that only 1% to 2% of C. fleckeri reported sting victims are even admitted to the hospital, with a total of five fatalities during the ten year span of the study. The majority of stings, while very painful, were minor and relieved in 15 to 20 minutes with cold pack application. (http://www.marine-medic.com.au/pages/articles/pdf/chironex.pdf)

The often repeated hype that 20-50 deaths per year by a related species in the Philippines was based on conjecture and anecdotal information. But that doesn't prevent the National Science Foundation from repeating it as a fact in their news releases. But you judge for yourself, here is the original conjecture- Fenner, Peter J. and John A. Williamson. "Worldwide deaths and severe envenomation from jellyfish stings." The Medical Journal of Australia 1996; 165; 658-661. (Sorry, don't have a free link.) Basically, they talked to fishermen in some remote Philippine villages and multiplied their stories of jellyfish deaths by the total number of fishing villages in the Philippines.

And I don't even know where someone pulled this factoid out of their nose- "There have been 5567 recorded deaths since 1954." Grin, there is a sucker born every minute, and it doesn't matter how often they get stung. Gseymour (talk) 23:07, 3 May 2012 (UTC)Reply

I've modified the relevant sentence in this article to better match the facts; "It [C. fleckeri] can cause excruciating pain to humans, sometimes followed by death." Less sensationalistic than the previous wording, but this time correct. If you find similar cases of unsupported and incorrect information, please do feel free to change it in the article itself. RN1970 (talk) 00:16, 4 August 2012 (UTC)Reply

Thank you for that change. I am a little gun-shy about editing pages directly, since I was accused of vandalism several years ago the first time I attempted an edit. I only whine in the talk pages, now, grin. Gseymour (talk) 19:11, 27 December 2012 (UTC)Reply

The article here, about Cnidocyte(s), mentions the term Stenotele. But there is no such link at wikipedia:

https://en.wikipedia.org/wiki/Stenotele

Could someone perhaps add this article about a Stenotele? It would make the article here seem more consistent if we can also click on the term meaning Stenotele. 2A02:8388:1604:CA80:F462:6A60:DEA:83A0 (talk) 23:09, 9 August 2018 (UTC)Reply