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I don't know if anyone has heard of this myth, but it might be worth including. I'm not sure I could do it and keep in tone with the article though. If no-one else has a go in a few days I might give it a shot. - FrancisTyers 18:14, 17 January 2006 (UTC)
Okay, what I'm about to say may make me sound like an idiot, but I'm okay with that. Last night I was watching animal planet because I couldn't go to sleep, and it said something about a fish that eats its own brain and turns into a plant, and I was like, 'whoa!'. So today I looked it up and found this article, but I seriously can't read it. I'm sorry, but it feels like you have to get a master's degree in science before you can read this article, so-- don't do this if it's really as stupid as it sounds-- maybe there could be a section that explains it in a nutshell, with normal people words. I obviously couldn't make it since I have know idea what this thing is talking about, but if someone would, it'd be nice. Sorry, I promise I'm not a valley girl!
He is right (first guy) tunicates are closely related to fish, and also digest the ganglion that is present in the tunicates larval stage. In a sense it "eats its brain". Also for the vanadium concentrations in tunicates, I beleive I have the answer. Tunicates use it as a defensive secretion on predators, it is a poison of sorts. More research could be put into this, but here are the beginnings.
59.96.103.5 ( talk) 03:37, 19 June 2008 (UTC)Well it says in the article like said by the person above me that the Tunicate larva when metamorphosing (or transforming) into the adult) undergoes many changes. In fact it can't even feed...its just a stage required for the dispersal the the tunicate species. So while changing, the dorsal nerve chord (a chordate character) is lost by the adult because it is digested by it. So comes the phrase "its eats it's own brain" not that it literaly does. This is all due to retrogressive metamorphosis which means transformation of the larval stage into adult....but by losing some characters. {perhaps the stalked adult body was mistaken for a plant body as it is also plant like in the sense that it cannot move and is fixed to the substratum} I tried to keep this simple....hope I was of some help! —Preceding unsigned comment added by 59.96.103.5 ( talk) 03:32, 19 June 2008 (UTC)
Biologists' in-joke
I'm not really sure if this is appropriate to the article, but I felt the need to mention it. The tunicate is the subject of an in-joke among biologists, namely that its act of "settling down and eating its own brain" is akin to a professor getting
tenure. --
FOo
23:27, 22 December 2006 (UTC)
"Our closest invertebrate relative, the humble sea squirt, can regenerate its entire body from just tiny blood vessel fragments, scientists now report.
The entire regeneration process, which in part resembles the early stages of embryonic development, can produce an adult sea squirt in as little as a week."
From http://www.livescience.com Full article here: http://www.livescience.com/animalworld/070305_blood_regeneration.html
Not having any background in the natural sciences, I have no idea how to properly include this information in the article. I hope someone can do this soon, as it seems pretty important.
24.46.61.185 23:48, 6 March 2007 (UTC)
Sea squirt currently redirects here, but it's also given as a synonym for Ascidiacea, and in my non-biologist opinion it would seem likelier that people searching for sea squirts are looking for the edible ones (all Ascidiacea spp) rather than other tunicates. Any objections to changing the redirect?
And that "sea pork" mention/reference should also be moved into Ascidiacea. Jpatokal ( talk) 17:47, 13 January 2008 (UTC)
I removed some links:
"New research suggests that sea squirts may not actually be chordates at all, but are species which may be some sort of mysterious hybrid between a chordate and an ancient sea urchin ancestor[citation needed]."
Sounds very dubious to me. I have never heard of anything like this, and most papers seem to strongly support that tunicates are included in Chordata. Also a chordate and an 'ancient sea urchin ancestor', whatever that is, couldn't hybridise. It has, rightly, been tagged with "citation needed", but I suggest we just remove this. —Preceding unsigned comment added by 92.8.249.254 ( talk) 17:31, 5 September 2009 (UTC)
Read this today in the newest issue of New Scientist; but New Scientist also fails to cite the reference and is itself simple a popular publication, not a primary source. I can't find anything in Google scholar relating to this. If a new primary scientific publication does not pop up very soon, I also strongly recommend removing this. -DWB, Paleobiology, UChicago 128.135.197.76 ( talk) 21:11, 5 September 2009 (UTC)
I also agree that the hybridization statement should be removed from the text. The idea has been long promoted by Donald Williamson and has received very little if any scientific support. It has attracted a fringe of the anti-evolution crowd. Here is a good review of his book promoting the idea [2] I suggest we take the statement out until better support is made for it. Wilson44691 ( talk) 23:02, 16 September 2009 (UTC)
New Scientist referred back to an earlier issue which carried a full article that did cite primary research, if my memory serves. I haven't dug it out yet but I put the NS reference in for the time being. NS may be a popular science journal but it's also a well-respected science journal and if it's important enough to get a mention in NS, it's surely important enough for Wikipedia. Our articles are based predominantly on secondary sources anyway. Sure, creationists have jumped on this research for their own purposes but this will happen in nearly any field. I can't see why scientific research is held to be discredited by the fact that some people are misusing or misrepresenting it. It isn't as if it's being stated as fact, and a single brief line on a new hypothesis in an article of this length doesn't seem like undue weight :) Gnostrat ( talk) 00:54, 17 September 2009 (UTC)
We also don't include in Wikipedia every idea on every topic. This particular hybridization hypothesis lacks any significant scientific support. It is not a small idea -- it is a big one which if true changes many fundamental concepts of embryology and evolution. It needs far more support from scientific research to make it into a scientific article. Note the first two comments above. I'm going to remove it until we hear more of the evidence for it and reach some sort of consensus on this discussion page. Wilson44691 ( talk) 01:21, 17 September 2009 (UTC)
You're right that genetic transfer across vast taxonomic distances is a revolutionary idea but what I'm finding is that it has far from insignificant support. So this particular hybridisation shouldn't be dismissed on that account. The 2007 article referenced in the 5 Sept issue of NS is evidently unrelated: sea squirts are introduced simply as an example of how loss of complexity in evolutionary lineages turns received phylogenetic assumptions on their head. However, the sea squirt hybrid hypothesis does get a mention in a different NS article: "Uprooting Darwin's tree" by Graham Lawton (24 January 2009, pp.34-39). This was the one I remembered, in part because it drew a critical letter from such luminaries as Daniel Dennett, Jerry Coyne and Richard Dawkins in the 21 February edition, not taking issue with the article's content (which, they argued, supports their position) but on account of a magazine cover which they considered had misrepresented it.
The article does summarise Donald Williamson's larval transfer hypothesis in a separate box as the position of "some researchers". But this is not the subject of the main text, which is largely about the prevalence of HGT (horizontal gene transfer) in microbes; how this is turning out to be evolutionarily significant in animals too, with viruses as the main cut-and-paste agents; and what this means for Darwin's tree of life concept (in a nutshell, the tree is not the only pattern: some evolutionary relationships are tree-like, but others are web-like). Evolutionary biologists quoted or cited in support of the widespread exchange of genetic material among groups include: W. Ford Doolittle (Dalhousie Univ., Halifax, Nova Scotia); Eric Bapteste (Pierre & Marie Curie Univ., Paris); Michael Rose (Univ. of California, Irvine); Tal Dagan & William Martin (Heinrich Heine Univ., Düsseldorf); John Dupré (Univ. of Exeter, UK); and James Mallet (University College London). Hybridisation is dealt with along the way, with Mallet pointing out that "ten percent of all animals regularly hybridise with other species".
This is where tunicates come in. The article cites " Cross-species gene transfer; implications for a new theory of evolution" by Michael Syvanen (Univ. of California) in Journal of Theoretical Biology 112 (2): 333-43 (January 1985) which predicted that 'natural-born chimeras' have shaped animal evolution. However, on his more recent testing of that claim, NS interviews him rather than cites published work. So I'm just going to quote this from p.39:
Syvanen recently compared 2000 genes that are common to humans, frogs, sea squirts, sea urchins, fruit flies and nematodes. In theory, he should have been able to use the gene sequences to construct an evolutionary tree showing the relationships between the six animals. He failed. The problem was that different genes told contradictory evolutionary stories. This was especially true of sea-squirt genes....Some genes did indeed cluster within the chordates, but others indicated that tunicates should be placed with sea urchins, which aren't chordates. "Roughly 50 per cent of its genes have one evolutionary history and 50 per cent another," Syvanen says. The most likely explanation for this, he argues, is that tunicates are chimeras, created by the fusion of an early chordate and an ancestor of the sea urchins around 600 million years ago. "We've just annihilated the tree of life. It's not a tree any more, it's a different topology entirely," says Syvanen.
If Syvanen has published, his paper must be out there somewhere and I'm sure you have the means to locate it. In the meantime, I would contend that the NS article is a good enough source for WP. It's good enough for Dennett, Coyne, Dawkins & Myers, even if they insist that "of course there's a tree, it's just more of a banyan than an oak". Gnostrat ( talk) 20:00, 17 September 2009 (UTC)
I think this statement is a good compromise, Gnostrat. As for citations, check out a 2007 paper in American Scientist by Williamson & Vickers. There is a pdf online. I'd give you the link but I can't figure out how to copy it. Google "hybridization larvae american scientist" and the pdf will show up. Cited in Williamson & Vickers is this paper: Hart, M. W. 1996. Testing cold fusion of phyla: Maternity in a tunicate × sea urchin hybrid determined from DNA comparisons. Evolution 50:1713–1718. It may be a good wiki citation as well, but I don't have immediate access to it. Here is my slight modification of the statement (mainly shortening it):
"Sea squirts have become a testing ground in the controversy about the extent to which cross-species gene transfer and hybridization have influenced animal evolution. In 1990, Donald I. Williamson of the University of Liverpool (U.K.) fertilised sea squirt (Ascidia mentula) eggs with sea urchin (Echinus esculentus) sperm resulting in fertile adults that resembled urchins [Williamson, D.I. & Vickers, S.E. (November-December 2007). The Origins of Larvae: Mismatches between the forms of adult animals and their larvae may reflect fused genomes, expressed in sequence in complex life histories. American Scientist 1021: 509-517.], but Michael W. Hart of Simon Fraser University failed to find sea-squirt DNA in tissue samples from the supposed hybrids [Hart, M.W. (1996). Testing cold fusion of phyla: Maternity in a tunicate × sea urchin hybrid determined from DNA comparisons. Evolution 50: 1713–1718.]. Williamson claims to have repeated the experiment with sea urchin eggs and sea squirt sperm, producing sea urchin larvae which developed into squirt-like juveniles [Williamson, D.I. (in press). Larval transfer: experimental hybrids. In: Margulis, L. & Asikainen, C.A. (editors), Chimeras and Consciousness: Evolution of Sensory Systems. White River Junction, Vermont: Chelsea Green Publishing Co. (cit. in: Williamson, D.I. & Vickers, S.E. Larval Transfer: A recent evolutionary theory. Ms. submitted to American Scientist).]. Michael Syvanen of the University of California has further suggested that sea squirts are themselves descended from a hybrid between a chordate and an ancestor of sea urchins [Lawton, G. (24 January 2009). Uprooting Darwin's tree. New Scientist 2692: 34-39.]. Like Williamson's, this idea has not yet gained support from embryologists and invertebrate zoologists."
This looks good to me, Gnostrat. It is a bit bulky, but certainly the reader has plenty of sources to consult, and there are adequate caveats in place. I say: publish! Good work. Wilson44691 ( talk) 23:43, 23 September 2009 (UTC)
Here's an interesting article on the latest reactions to and controversies about Williamson's work. [3] Wilson44691 ( talk) 20:19, 1 October 2009 (UTC)
I am a little unclear on what this page signifies, but I posted an update and a clarification of my results concerning the chimeric origin of the tunicates on the main wikipedia page. First a reference to the paper is given. Second, the result is that the hybridization event likely occured between a primitive chordate and protostome, not an ancestral echinoderm. M. Syvanen —Preceding unsigned comment added by 168.150.241.76 ( talk) 02:24, 11 June 2010 (UTC)
Nobody has any reputation at stake here. Nobody has anything to "lose" from a controversial claim in this debate. There is nothing to gain from "suppressing" opposing view points. In fact, every single tunicate biologist would jump at the opportunity to follow up on something exciting like this could be, if it were at all grounded in reality. The best way to make a name for yourself in biology is to prove dogma wrong. If a whole new avenue of research opens up, you can get funding and keep your career going. Sounds exactly why somebody would concoct a fishy "controversy" out of thin air to begin with... but I digress. As I was saying people would have every reason in the world to pursue a new controversial idea. The fact nobody has done so only speaks to how infantile these ideas are. I mean, where do you even begin? It's biologically akin to claiming water is not wet. How do you even work to refute that without looking like a total sucker? It's a lose-lose scenario. So, the conspiracy theories floating here about how these ideas are being silenced because they are "controversial" is laughable. How about, these ideas are being ignored because they sound like the answers a five year-old would write on a university-level exam. — Preceding unsigned comment added by 128.122.60.133 ( talk) 22:07, 29 July 2014 (UTC)
Oh, on 'Blue Planet: Deep Seas' on Discovery Channel, it was mentioned that there is a deep sea member of the tunicate group that's a carnivore. Could someone research this and update the diet bit on the main page with this weird rarity? —Preceding unsigned comment added by 198.69.249.94 ( talk) 01:36, 15 March 2010 (UTC)
Personal communication was listed as a general reference to this article. Because personal communications are not verifiable, they are unacceptable as Wikipedia sources. The reference was not linked to any specific statement so this calls into question the verifiability of all the unsourced material in this article. If the editor who added this reference could remove or resource any of the information tied to it, that would be very helpful. If not, perhaps a careful look at unsourced statements is warranted. -- Danger ( talk) 09:06, 22 November 2009 (UTC)
The article doesn't talk about where the tunicates get their vanadium, but it has apparently gotten some chemists working, as I read here: http://pipeline.corante.com/archives/2008/04/08/fun_with_tunichromes.php Someone may wish to include some of this into the article, as things develop. Wyvern ( talk) 06:12, 30 December 2010 (UTC)
Someone had stated that: "They were historically known as Ascadia, and are now commonly known as sea squirts". At first I thought it was a simple misspelling and corrected it. Then I realised that as it stood it didn't seem to mean anything, but as far as it might, it was wrong. I have deleted it and applied some minor corrections and refs pending anyone wishing to zap it again. If that happens, it had better be well supported. In checking my facts I found that the erroneous statement has been uncritically propagated across the Web; some people take WP material as gospel. JonRichfield ( talk) 15:52, 8 September 2011 (UTC)
http://www.pnas.org/content/102/42/15134.full
Transposon-mediated insertional mutagenesis revealed the functions of animal cellulose synthase in the ascidian Ciona intestinalis — Preceding unsigned comment added by 176.61.26.216 ( talk) 21:39, 30 November 2011 (UTC)
In some classes, the adults remain pelagic (swimming or drifting in the open sea), although their larvae undergo similar metamorphoses to a higher or lower degree.
Um, does this mean that the adults never mature, but their larvae do? Or what? And how can there be "degrees" of metamorphosis? And the article also says, The larval form is not capable of feeding, so does this mean that a non-metamorphosing adult never eats its whole life? The statement is slightly confusing. (I'm a laywoman, btw.) I guess it sorta makes sense, it's just not the most clear thing and could stand to be reworded so you don't have to think about it so much to understand it. StoryMakerEchidna ( talk) 19:26, 15 August 2012 (UTC)
It currently is contested whether tunicates or lancelets are the most closely related to vertebrates [4], and hence some sources are treating tunicates as a separate phylum from cordates. (Of course, this can't really be resolved fully before the question of hybrid sea-urchin/chordate origins..) Cesiumfrog ( talk) 11:53, 28 October 2012 (UTC)
GA toolbox |
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Reviewing |
Reviewer: Jens Lallensack ( talk · contribs) 11:43, 21 September 2013 (UTC)
I'm glad to review this article. -- Jens Lallensack ( talk) 11:43, 21 September 2013 (UTC)
Unfortunately I will not be able to complete the review before the weekend … but here is the major part. All in all, I think it is a very accurate article. The only weakness I can see is comprehensibility – the layperson may will have problems to follow. Most commens below aim to improve comprehensibility, though this is not needed for reaching GA. I hope that they help, if not, please ignore them.
Lead:
Anatomy:
Life cycle:
Taxonomy:
The main page says "that although a tunicate is an invertebrate, its larva (pictured) may have a notochord and resemble a small tadpole?"
But this article and the chordate article states it does have a notochord. Please correct the quote on the main page to reflect scientific definitions. If an organism is defined by a characteristic, chordata, for example, please do not rewrite that characteristic. Bad science! — Preceding unsigned comment added by 166.147.88.25 ( talk) 18:33, 20 October 2013 (UTC)
This paragraph is about the study, not the classification of tunicates, and this information should not dwarf that section. Tunicate classification is very important to the study of the evolution of animals, and this section of the article should reflect that. If this is added back to the article, it should put the study in its scientific context and address the relationship of the study to current classifications of tunicates and animals as all the secondary sources do.
{{
cite journal}}
: CS1 maint: multiple names: authors list (
link)
{{
cite journal}}
: CS1 maint: multiple names: authors list (
link)
--( AfadsBad ( talk) 15:34, 8 February 2014 (UTC))
Since there seems to be some disagreement about the subphylum name, could we have it here on the talk page rather than multiple edits? After looking into it, WORMS lists Tunicata as valid and Urochordata as invalid based on Margulis, L.; Schwartz, K.V. (1998). Five Kingdoms: an illustrated guide to the Phyla of life on earth. 3rd edition. Freeman: New York, NY (USA).
ISBN
0-7167-3027-8. xx, 520 pp. This record was updated 2005.
ITIS is the other way around, citing M. Ruggiero & D. Gordon, eds. 2013. Consensus Management Hierarchy for the ITIS & Species2000 Catalogue of Life, with a note "See Wells & Houston, eds. (1998), who use Tunicata rather than Urochordata. Both terms are in use, but apparently most specialists currently use Tunicata."
I just checked what I own, and every single book and identification resource lists Urochordata, which may be where the confusion comes from. The dates of them range from 1977 to 2013. What happens when conflicting resources arise like this?
Esox
id
talk•
contribs
19:19, 10 May 2014 (UTC)
This "controversy" has no legs. Are we to add every idiotic musing anybody has ever had about a subject to said subject's wikipedia page? It was a hypothesis put forth by a random dude in a non-peer-reviewed outlet run by predatory vanity publishers, a guy who doesn't even study tunicates for that matter. It's a hypothesis that does not make any biological sense and was instantly refuted by the several tunicate genomes sequenced, assembled, and freely available starting in 2002, and the tens of thousands of tunicate genes sequenced and analyzed since. This massive amount of data all points to a single origin of tunicates from a common ancestor that also gave rise to the vertebrates.
Were there ever any studies to refute this "controversial" claim? No. Why? Well there was no data to back the claim in the first place, so why should others waste their time getting hard data when the burden of proof should be on the one making the illogical claim in the first place? It's like claiming Elvis lives in my basement, putting that on the Elvis Wikipedia page until the press come over to my house and write articles proving my claims were a bunch of baloney.
Contrary to what people might imagine, nobody has anything to "lose" from a controversial claim in this debate. There is nothing to gain from "suppressing" opposing view points. This is sea squirt research we are talking about. Not exactly high stakes. In fact, every single tunicate biologist would jump at the opportunity to follow up on something exciting like this could be, if it were at all grounded in reality. The best way to make a name for yourself in biology is to prove dogma wrong. If a whole new avenue of research opens up, you can get funding and keep your career going. People would have every reason in the world to want to believe a new controversial theory, or at least follow it up. The fact nobody has done so only speaks to how infantile these ideas are. I mean, where do you even begin? It's biologically akin to claiming water is not wet. How do you even work to refute that without looking like a total sucker? So, the conspiracy theories floating here about how these ideas are being silenced because they are "controversial" is laughable. How about, these ideas are being ignored because they sound like the answers a five year-old would write on a university-level exam. — Preceding unsigned comment added by 128.122.60.133 ( talk) 21:21, 29 July 2014 (UTC)
My understanding is that Williamson's "hybridogenesis" hypothesis is generally regarded as a fringe theory, his work has not been successfully replicated or validated by other scientists, and his ideas have gained little to no traction in mainstream evolutionary or developmental biology. Most likely the material about the purported cross-phylum hybridization should be covered in Williamson's article but omitted here until it gains some more scholarly support. Thoughts? 73.223.96.73 ( talk) 05:28, 23 April 2015 (UTC)
I was reading through the related articles and claims as to the number of species do not match. Articles state that sea squirts are one of several types of Tunicate. The Tunicate article says there are 2150 species of tunicate. The Sea squirt article says there are 2300 species of sea squirts. This is clearly illogical, there must be more tunicate species than sea squirts if the tunicates includes te sea squirts? Carl wev 13:30, 7 August 2015 (UTC)
Sea squirt redirects to Ascidiacea, while Sea squirts, Sea Squirt and Sea Squirts redirect to Tunicate. I have propose that the latter three be retargetted so all point to Ascidiacea - you are invited to the discussion at Wikipedia:Redirects for discussion/Log/2018 September 17#Sea squirt. Please leave any comments there to keep discussion in one place. Thryduulf ( talk) 01:10, 17 September 2018 (UTC)
I do not want to put a great weight to the question of precedence to invalid synonyms:-). However, I note, that the taxobox gives 1877 Lankaster as year and authority for the name "urochordata", while WoRMS here gives 1874 Haeckel. Unless someone can resolve this with relatively little effort, I do not think that this should force a correction of the taxobox.
On the other hand, in either case, the suggestion of the name "urochorda" in the '80's would not be a second but a third name. I rephrased the second paragraph of the [[Tunicate#Taxonomy|]] section slightly, to make it into (IMHO) better accordance with the given facts. (Again, I do not find this very important; and I also is no expert in the field. If editors with a deeper knowledge of the facts prefer to revert this, please do!) JoergenB ( talk) 15:45, 24 December 2019 (UTC)
Lankester (1877, p. 439) mentioned the group ‘Urochordate Vertebrata’ for the Tunicata, and the Latin form ‘Urochorda’ was used in the table p. 441.. He accepts a name used first in the vernacular and subsequently latinised. He doesn't mention Haeckel and as the article is about authorship of higher chordate taxa and specifically discusses Haeckel's naming of Chordata I'm inclined to accept his view. I couldn't find Haeckel's 1874 edition of Anthropogenie oder Entwicklungsgeschichte des Menschen but the 1877 3rd edition and 1910 edition had no mention of Urochordata, while the later only mentions Chordata in a reference by Bateson (1879). My search is a quick one, but is consistent with Nielsen's attribution to Lankester (1877).
References
The section Taxonomy ("About 2,150 species") and Classification ("The Tunicata contain roughly 3,051 described species") contradict each other. The latter has a literature reference, but I don't know what the more accurate number is. — Preceding unsigned comment added by 159.230.53.88 ( talk) 15:13, 23 November 2020 (UTC)
References
The picture on this page with the pretty blue tunicates is indicated to be of Clavelina moluccensis, but is also used on the page for C. coerulea. It can't be both. Suttkus ( talk) 07:15, 24 May 2023 (UTC)
as far as is known, tunicates are the only animals known that can make cellulose; this is so unusual it really deservers its own section also here are two papers which discuss phylogeny; I would take the second as the latest word from the specialists https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3306355/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10325964/ — Preceding unsigned comment added by 50.245.17.105 ( talk) 19:34, 14 March 2024 (UTC)
Tunicate has been listed as one of the
Natural sciences good articles under the
good article criteria. If you can improve it further,
please do so. If it no longer meets these criteria, you can
reassess it. Review: October 1, 2013. ( Reviewed version). |
This
level-5 vital article is rated GA-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||||||||||||||||||||||||||
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I don't know if anyone has heard of this myth, but it might be worth including. I'm not sure I could do it and keep in tone with the article though. If no-one else has a go in a few days I might give it a shot. - FrancisTyers 18:14, 17 January 2006 (UTC)
Okay, what I'm about to say may make me sound like an idiot, but I'm okay with that. Last night I was watching animal planet because I couldn't go to sleep, and it said something about a fish that eats its own brain and turns into a plant, and I was like, 'whoa!'. So today I looked it up and found this article, but I seriously can't read it. I'm sorry, but it feels like you have to get a master's degree in science before you can read this article, so-- don't do this if it's really as stupid as it sounds-- maybe there could be a section that explains it in a nutshell, with normal people words. I obviously couldn't make it since I have know idea what this thing is talking about, but if someone would, it'd be nice. Sorry, I promise I'm not a valley girl!
He is right (first guy) tunicates are closely related to fish, and also digest the ganglion that is present in the tunicates larval stage. In a sense it "eats its brain". Also for the vanadium concentrations in tunicates, I beleive I have the answer. Tunicates use it as a defensive secretion on predators, it is a poison of sorts. More research could be put into this, but here are the beginnings.
59.96.103.5 ( talk) 03:37, 19 June 2008 (UTC)Well it says in the article like said by the person above me that the Tunicate larva when metamorphosing (or transforming) into the adult) undergoes many changes. In fact it can't even feed...its just a stage required for the dispersal the the tunicate species. So while changing, the dorsal nerve chord (a chordate character) is lost by the adult because it is digested by it. So comes the phrase "its eats it's own brain" not that it literaly does. This is all due to retrogressive metamorphosis which means transformation of the larval stage into adult....but by losing some characters. {perhaps the stalked adult body was mistaken for a plant body as it is also plant like in the sense that it cannot move and is fixed to the substratum} I tried to keep this simple....hope I was of some help! —Preceding unsigned comment added by 59.96.103.5 ( talk) 03:32, 19 June 2008 (UTC)
Biologists' in-joke
I'm not really sure if this is appropriate to the article, but I felt the need to mention it. The tunicate is the subject of an in-joke among biologists, namely that its act of "settling down and eating its own brain" is akin to a professor getting
tenure. --
FOo
23:27, 22 December 2006 (UTC)
"Our closest invertebrate relative, the humble sea squirt, can regenerate its entire body from just tiny blood vessel fragments, scientists now report.
The entire regeneration process, which in part resembles the early stages of embryonic development, can produce an adult sea squirt in as little as a week."
From http://www.livescience.com Full article here: http://www.livescience.com/animalworld/070305_blood_regeneration.html
Not having any background in the natural sciences, I have no idea how to properly include this information in the article. I hope someone can do this soon, as it seems pretty important.
24.46.61.185 23:48, 6 March 2007 (UTC)
Sea squirt currently redirects here, but it's also given as a synonym for Ascidiacea, and in my non-biologist opinion it would seem likelier that people searching for sea squirts are looking for the edible ones (all Ascidiacea spp) rather than other tunicates. Any objections to changing the redirect?
And that "sea pork" mention/reference should also be moved into Ascidiacea. Jpatokal ( talk) 17:47, 13 January 2008 (UTC)
I removed some links:
"New research suggests that sea squirts may not actually be chordates at all, but are species which may be some sort of mysterious hybrid between a chordate and an ancient sea urchin ancestor[citation needed]."
Sounds very dubious to me. I have never heard of anything like this, and most papers seem to strongly support that tunicates are included in Chordata. Also a chordate and an 'ancient sea urchin ancestor', whatever that is, couldn't hybridise. It has, rightly, been tagged with "citation needed", but I suggest we just remove this. —Preceding unsigned comment added by 92.8.249.254 ( talk) 17:31, 5 September 2009 (UTC)
Read this today in the newest issue of New Scientist; but New Scientist also fails to cite the reference and is itself simple a popular publication, not a primary source. I can't find anything in Google scholar relating to this. If a new primary scientific publication does not pop up very soon, I also strongly recommend removing this. -DWB, Paleobiology, UChicago 128.135.197.76 ( talk) 21:11, 5 September 2009 (UTC)
I also agree that the hybridization statement should be removed from the text. The idea has been long promoted by Donald Williamson and has received very little if any scientific support. It has attracted a fringe of the anti-evolution crowd. Here is a good review of his book promoting the idea [2] I suggest we take the statement out until better support is made for it. Wilson44691 ( talk) 23:02, 16 September 2009 (UTC)
New Scientist referred back to an earlier issue which carried a full article that did cite primary research, if my memory serves. I haven't dug it out yet but I put the NS reference in for the time being. NS may be a popular science journal but it's also a well-respected science journal and if it's important enough to get a mention in NS, it's surely important enough for Wikipedia. Our articles are based predominantly on secondary sources anyway. Sure, creationists have jumped on this research for their own purposes but this will happen in nearly any field. I can't see why scientific research is held to be discredited by the fact that some people are misusing or misrepresenting it. It isn't as if it's being stated as fact, and a single brief line on a new hypothesis in an article of this length doesn't seem like undue weight :) Gnostrat ( talk) 00:54, 17 September 2009 (UTC)
We also don't include in Wikipedia every idea on every topic. This particular hybridization hypothesis lacks any significant scientific support. It is not a small idea -- it is a big one which if true changes many fundamental concepts of embryology and evolution. It needs far more support from scientific research to make it into a scientific article. Note the first two comments above. I'm going to remove it until we hear more of the evidence for it and reach some sort of consensus on this discussion page. Wilson44691 ( talk) 01:21, 17 September 2009 (UTC)
You're right that genetic transfer across vast taxonomic distances is a revolutionary idea but what I'm finding is that it has far from insignificant support. So this particular hybridisation shouldn't be dismissed on that account. The 2007 article referenced in the 5 Sept issue of NS is evidently unrelated: sea squirts are introduced simply as an example of how loss of complexity in evolutionary lineages turns received phylogenetic assumptions on their head. However, the sea squirt hybrid hypothesis does get a mention in a different NS article: "Uprooting Darwin's tree" by Graham Lawton (24 January 2009, pp.34-39). This was the one I remembered, in part because it drew a critical letter from such luminaries as Daniel Dennett, Jerry Coyne and Richard Dawkins in the 21 February edition, not taking issue with the article's content (which, they argued, supports their position) but on account of a magazine cover which they considered had misrepresented it.
The article does summarise Donald Williamson's larval transfer hypothesis in a separate box as the position of "some researchers". But this is not the subject of the main text, which is largely about the prevalence of HGT (horizontal gene transfer) in microbes; how this is turning out to be evolutionarily significant in animals too, with viruses as the main cut-and-paste agents; and what this means for Darwin's tree of life concept (in a nutshell, the tree is not the only pattern: some evolutionary relationships are tree-like, but others are web-like). Evolutionary biologists quoted or cited in support of the widespread exchange of genetic material among groups include: W. Ford Doolittle (Dalhousie Univ., Halifax, Nova Scotia); Eric Bapteste (Pierre & Marie Curie Univ., Paris); Michael Rose (Univ. of California, Irvine); Tal Dagan & William Martin (Heinrich Heine Univ., Düsseldorf); John Dupré (Univ. of Exeter, UK); and James Mallet (University College London). Hybridisation is dealt with along the way, with Mallet pointing out that "ten percent of all animals regularly hybridise with other species".
This is where tunicates come in. The article cites " Cross-species gene transfer; implications for a new theory of evolution" by Michael Syvanen (Univ. of California) in Journal of Theoretical Biology 112 (2): 333-43 (January 1985) which predicted that 'natural-born chimeras' have shaped animal evolution. However, on his more recent testing of that claim, NS interviews him rather than cites published work. So I'm just going to quote this from p.39:
Syvanen recently compared 2000 genes that are common to humans, frogs, sea squirts, sea urchins, fruit flies and nematodes. In theory, he should have been able to use the gene sequences to construct an evolutionary tree showing the relationships between the six animals. He failed. The problem was that different genes told contradictory evolutionary stories. This was especially true of sea-squirt genes....Some genes did indeed cluster within the chordates, but others indicated that tunicates should be placed with sea urchins, which aren't chordates. "Roughly 50 per cent of its genes have one evolutionary history and 50 per cent another," Syvanen says. The most likely explanation for this, he argues, is that tunicates are chimeras, created by the fusion of an early chordate and an ancestor of the sea urchins around 600 million years ago. "We've just annihilated the tree of life. It's not a tree any more, it's a different topology entirely," says Syvanen.
If Syvanen has published, his paper must be out there somewhere and I'm sure you have the means to locate it. In the meantime, I would contend that the NS article is a good enough source for WP. It's good enough for Dennett, Coyne, Dawkins & Myers, even if they insist that "of course there's a tree, it's just more of a banyan than an oak". Gnostrat ( talk) 20:00, 17 September 2009 (UTC)
I think this statement is a good compromise, Gnostrat. As for citations, check out a 2007 paper in American Scientist by Williamson & Vickers. There is a pdf online. I'd give you the link but I can't figure out how to copy it. Google "hybridization larvae american scientist" and the pdf will show up. Cited in Williamson & Vickers is this paper: Hart, M. W. 1996. Testing cold fusion of phyla: Maternity in a tunicate × sea urchin hybrid determined from DNA comparisons. Evolution 50:1713–1718. It may be a good wiki citation as well, but I don't have immediate access to it. Here is my slight modification of the statement (mainly shortening it):
"Sea squirts have become a testing ground in the controversy about the extent to which cross-species gene transfer and hybridization have influenced animal evolution. In 1990, Donald I. Williamson of the University of Liverpool (U.K.) fertilised sea squirt (Ascidia mentula) eggs with sea urchin (Echinus esculentus) sperm resulting in fertile adults that resembled urchins [Williamson, D.I. & Vickers, S.E. (November-December 2007). The Origins of Larvae: Mismatches between the forms of adult animals and their larvae may reflect fused genomes, expressed in sequence in complex life histories. American Scientist 1021: 509-517.], but Michael W. Hart of Simon Fraser University failed to find sea-squirt DNA in tissue samples from the supposed hybrids [Hart, M.W. (1996). Testing cold fusion of phyla: Maternity in a tunicate × sea urchin hybrid determined from DNA comparisons. Evolution 50: 1713–1718.]. Williamson claims to have repeated the experiment with sea urchin eggs and sea squirt sperm, producing sea urchin larvae which developed into squirt-like juveniles [Williamson, D.I. (in press). Larval transfer: experimental hybrids. In: Margulis, L. & Asikainen, C.A. (editors), Chimeras and Consciousness: Evolution of Sensory Systems. White River Junction, Vermont: Chelsea Green Publishing Co. (cit. in: Williamson, D.I. & Vickers, S.E. Larval Transfer: A recent evolutionary theory. Ms. submitted to American Scientist).]. Michael Syvanen of the University of California has further suggested that sea squirts are themselves descended from a hybrid between a chordate and an ancestor of sea urchins [Lawton, G. (24 January 2009). Uprooting Darwin's tree. New Scientist 2692: 34-39.]. Like Williamson's, this idea has not yet gained support from embryologists and invertebrate zoologists."
This looks good to me, Gnostrat. It is a bit bulky, but certainly the reader has plenty of sources to consult, and there are adequate caveats in place. I say: publish! Good work. Wilson44691 ( talk) 23:43, 23 September 2009 (UTC)
Here's an interesting article on the latest reactions to and controversies about Williamson's work. [3] Wilson44691 ( talk) 20:19, 1 October 2009 (UTC)
I am a little unclear on what this page signifies, but I posted an update and a clarification of my results concerning the chimeric origin of the tunicates on the main wikipedia page. First a reference to the paper is given. Second, the result is that the hybridization event likely occured between a primitive chordate and protostome, not an ancestral echinoderm. M. Syvanen —Preceding unsigned comment added by 168.150.241.76 ( talk) 02:24, 11 June 2010 (UTC)
Nobody has any reputation at stake here. Nobody has anything to "lose" from a controversial claim in this debate. There is nothing to gain from "suppressing" opposing view points. In fact, every single tunicate biologist would jump at the opportunity to follow up on something exciting like this could be, if it were at all grounded in reality. The best way to make a name for yourself in biology is to prove dogma wrong. If a whole new avenue of research opens up, you can get funding and keep your career going. Sounds exactly why somebody would concoct a fishy "controversy" out of thin air to begin with... but I digress. As I was saying people would have every reason in the world to pursue a new controversial idea. The fact nobody has done so only speaks to how infantile these ideas are. I mean, where do you even begin? It's biologically akin to claiming water is not wet. How do you even work to refute that without looking like a total sucker? It's a lose-lose scenario. So, the conspiracy theories floating here about how these ideas are being silenced because they are "controversial" is laughable. How about, these ideas are being ignored because they sound like the answers a five year-old would write on a university-level exam. — Preceding unsigned comment added by 128.122.60.133 ( talk) 22:07, 29 July 2014 (UTC)
Oh, on 'Blue Planet: Deep Seas' on Discovery Channel, it was mentioned that there is a deep sea member of the tunicate group that's a carnivore. Could someone research this and update the diet bit on the main page with this weird rarity? —Preceding unsigned comment added by 198.69.249.94 ( talk) 01:36, 15 March 2010 (UTC)
Personal communication was listed as a general reference to this article. Because personal communications are not verifiable, they are unacceptable as Wikipedia sources. The reference was not linked to any specific statement so this calls into question the verifiability of all the unsourced material in this article. If the editor who added this reference could remove or resource any of the information tied to it, that would be very helpful. If not, perhaps a careful look at unsourced statements is warranted. -- Danger ( talk) 09:06, 22 November 2009 (UTC)
The article doesn't talk about where the tunicates get their vanadium, but it has apparently gotten some chemists working, as I read here: http://pipeline.corante.com/archives/2008/04/08/fun_with_tunichromes.php Someone may wish to include some of this into the article, as things develop. Wyvern ( talk) 06:12, 30 December 2010 (UTC)
Someone had stated that: "They were historically known as Ascadia, and are now commonly known as sea squirts". At first I thought it was a simple misspelling and corrected it. Then I realised that as it stood it didn't seem to mean anything, but as far as it might, it was wrong. I have deleted it and applied some minor corrections and refs pending anyone wishing to zap it again. If that happens, it had better be well supported. In checking my facts I found that the erroneous statement has been uncritically propagated across the Web; some people take WP material as gospel. JonRichfield ( talk) 15:52, 8 September 2011 (UTC)
http://www.pnas.org/content/102/42/15134.full
Transposon-mediated insertional mutagenesis revealed the functions of animal cellulose synthase in the ascidian Ciona intestinalis — Preceding unsigned comment added by 176.61.26.216 ( talk) 21:39, 30 November 2011 (UTC)
In some classes, the adults remain pelagic (swimming or drifting in the open sea), although their larvae undergo similar metamorphoses to a higher or lower degree.
Um, does this mean that the adults never mature, but their larvae do? Or what? And how can there be "degrees" of metamorphosis? And the article also says, The larval form is not capable of feeding, so does this mean that a non-metamorphosing adult never eats its whole life? The statement is slightly confusing. (I'm a laywoman, btw.) I guess it sorta makes sense, it's just not the most clear thing and could stand to be reworded so you don't have to think about it so much to understand it. StoryMakerEchidna ( talk) 19:26, 15 August 2012 (UTC)
It currently is contested whether tunicates or lancelets are the most closely related to vertebrates [4], and hence some sources are treating tunicates as a separate phylum from cordates. (Of course, this can't really be resolved fully before the question of hybrid sea-urchin/chordate origins..) Cesiumfrog ( talk) 11:53, 28 October 2012 (UTC)
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Reviewer: Jens Lallensack ( talk · contribs) 11:43, 21 September 2013 (UTC)
I'm glad to review this article. -- Jens Lallensack ( talk) 11:43, 21 September 2013 (UTC)
Unfortunately I will not be able to complete the review before the weekend … but here is the major part. All in all, I think it is a very accurate article. The only weakness I can see is comprehensibility – the layperson may will have problems to follow. Most commens below aim to improve comprehensibility, though this is not needed for reaching GA. I hope that they help, if not, please ignore them.
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Anatomy:
Life cycle:
Taxonomy:
The main page says "that although a tunicate is an invertebrate, its larva (pictured) may have a notochord and resemble a small tadpole?"
But this article and the chordate article states it does have a notochord. Please correct the quote on the main page to reflect scientific definitions. If an organism is defined by a characteristic, chordata, for example, please do not rewrite that characteristic. Bad science! — Preceding unsigned comment added by 166.147.88.25 ( talk) 18:33, 20 October 2013 (UTC)
This paragraph is about the study, not the classification of tunicates, and this information should not dwarf that section. Tunicate classification is very important to the study of the evolution of animals, and this section of the article should reflect that. If this is added back to the article, it should put the study in its scientific context and address the relationship of the study to current classifications of tunicates and animals as all the secondary sources do.
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Since there seems to be some disagreement about the subphylum name, could we have it here on the talk page rather than multiple edits? After looking into it, WORMS lists Tunicata as valid and Urochordata as invalid based on Margulis, L.; Schwartz, K.V. (1998). Five Kingdoms: an illustrated guide to the Phyla of life on earth. 3rd edition. Freeman: New York, NY (USA).
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0-7167-3027-8. xx, 520 pp. This record was updated 2005.
ITIS is the other way around, citing M. Ruggiero & D. Gordon, eds. 2013. Consensus Management Hierarchy for the ITIS & Species2000 Catalogue of Life, with a note "See Wells & Houston, eds. (1998), who use Tunicata rather than Urochordata. Both terms are in use, but apparently most specialists currently use Tunicata."
I just checked what I own, and every single book and identification resource lists Urochordata, which may be where the confusion comes from. The dates of them range from 1977 to 2013. What happens when conflicting resources arise like this?
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19:19, 10 May 2014 (UTC)
This "controversy" has no legs. Are we to add every idiotic musing anybody has ever had about a subject to said subject's wikipedia page? It was a hypothesis put forth by a random dude in a non-peer-reviewed outlet run by predatory vanity publishers, a guy who doesn't even study tunicates for that matter. It's a hypothesis that does not make any biological sense and was instantly refuted by the several tunicate genomes sequenced, assembled, and freely available starting in 2002, and the tens of thousands of tunicate genes sequenced and analyzed since. This massive amount of data all points to a single origin of tunicates from a common ancestor that also gave rise to the vertebrates.
Were there ever any studies to refute this "controversial" claim? No. Why? Well there was no data to back the claim in the first place, so why should others waste their time getting hard data when the burden of proof should be on the one making the illogical claim in the first place? It's like claiming Elvis lives in my basement, putting that on the Elvis Wikipedia page until the press come over to my house and write articles proving my claims were a bunch of baloney.
Contrary to what people might imagine, nobody has anything to "lose" from a controversial claim in this debate. There is nothing to gain from "suppressing" opposing view points. This is sea squirt research we are talking about. Not exactly high stakes. In fact, every single tunicate biologist would jump at the opportunity to follow up on something exciting like this could be, if it were at all grounded in reality. The best way to make a name for yourself in biology is to prove dogma wrong. If a whole new avenue of research opens up, you can get funding and keep your career going. People would have every reason in the world to want to believe a new controversial theory, or at least follow it up. The fact nobody has done so only speaks to how infantile these ideas are. I mean, where do you even begin? It's biologically akin to claiming water is not wet. How do you even work to refute that without looking like a total sucker? So, the conspiracy theories floating here about how these ideas are being silenced because they are "controversial" is laughable. How about, these ideas are being ignored because they sound like the answers a five year-old would write on a university-level exam. — Preceding unsigned comment added by 128.122.60.133 ( talk) 21:21, 29 July 2014 (UTC)
My understanding is that Williamson's "hybridogenesis" hypothesis is generally regarded as a fringe theory, his work has not been successfully replicated or validated by other scientists, and his ideas have gained little to no traction in mainstream evolutionary or developmental biology. Most likely the material about the purported cross-phylum hybridization should be covered in Williamson's article but omitted here until it gains some more scholarly support. Thoughts? 73.223.96.73 ( talk) 05:28, 23 April 2015 (UTC)
I was reading through the related articles and claims as to the number of species do not match. Articles state that sea squirts are one of several types of Tunicate. The Tunicate article says there are 2150 species of tunicate. The Sea squirt article says there are 2300 species of sea squirts. This is clearly illogical, there must be more tunicate species than sea squirts if the tunicates includes te sea squirts? Carl wev 13:30, 7 August 2015 (UTC)
Sea squirt redirects to Ascidiacea, while Sea squirts, Sea Squirt and Sea Squirts redirect to Tunicate. I have propose that the latter three be retargetted so all point to Ascidiacea - you are invited to the discussion at Wikipedia:Redirects for discussion/Log/2018 September 17#Sea squirt. Please leave any comments there to keep discussion in one place. Thryduulf ( talk) 01:10, 17 September 2018 (UTC)
I do not want to put a great weight to the question of precedence to invalid synonyms:-). However, I note, that the taxobox gives 1877 Lankaster as year and authority for the name "urochordata", while WoRMS here gives 1874 Haeckel. Unless someone can resolve this with relatively little effort, I do not think that this should force a correction of the taxobox.
On the other hand, in either case, the suggestion of the name "urochorda" in the '80's would not be a second but a third name. I rephrased the second paragraph of the [[Tunicate#Taxonomy|]] section slightly, to make it into (IMHO) better accordance with the given facts. (Again, I do not find this very important; and I also is no expert in the field. If editors with a deeper knowledge of the facts prefer to revert this, please do!) JoergenB ( talk) 15:45, 24 December 2019 (UTC)
Lankester (1877, p. 439) mentioned the group ‘Urochordate Vertebrata’ for the Tunicata, and the Latin form ‘Urochorda’ was used in the table p. 441.. He accepts a name used first in the vernacular and subsequently latinised. He doesn't mention Haeckel and as the article is about authorship of higher chordate taxa and specifically discusses Haeckel's naming of Chordata I'm inclined to accept his view. I couldn't find Haeckel's 1874 edition of Anthropogenie oder Entwicklungsgeschichte des Menschen but the 1877 3rd edition and 1910 edition had no mention of Urochordata, while the later only mentions Chordata in a reference by Bateson (1879). My search is a quick one, but is consistent with Nielsen's attribution to Lankester (1877).
References
The section Taxonomy ("About 2,150 species") and Classification ("The Tunicata contain roughly 3,051 described species") contradict each other. The latter has a literature reference, but I don't know what the more accurate number is. — Preceding unsigned comment added by 159.230.53.88 ( talk) 15:13, 23 November 2020 (UTC)
References
The picture on this page with the pretty blue tunicates is indicated to be of Clavelina moluccensis, but is also used on the page for C. coerulea. It can't be both. Suttkus ( talk) 07:15, 24 May 2023 (UTC)
as far as is known, tunicates are the only animals known that can make cellulose; this is so unusual it really deservers its own section also here are two papers which discuss phylogeny; I would take the second as the latest word from the specialists https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3306355/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10325964/ — Preceding unsigned comment added by 50.245.17.105 ( talk) 19:34, 14 March 2024 (UTC)