Talk:Onychophora

Translation from German

There is an excellent (and acknowledged as such) article on these creatures at the German wikipedia. I've started a translation but it may take a while because the article is enormous and contains a lot of technical detail. Yummifruitbat 00:44, 14 November 2005 (UTC)

Just to update, I got about 6 paragraphs into the translation and then my real life workload picked up pretty heavily. I'd sort of forgotten about this until Richard001 asked me whether I was still working on it. The answer is, currently, no, but I'd like to pick it back up again when I've finished uni which will be in about 2 months' time. I'll make it a priority then, but in the mean time if someone else wants to tackle it I won't protest. Sorry to have left it for so long. --YFB ¿ 12:44, 27 April 2007 (UTC)

Placenta?

Onychophorans are among the few animals other than mammals with placentas. Most species, including Epiperipatus biolleyi, give live birth. (National Geographic, October 1993, p. 136)

What are the other non-mammal animals to have placentas? This is amazing! -- Toytoy 14:19, 26 November 2005 (UTC)

Is this actually true? Why isn't it in the article? The Jade Knight 00:11, 13 March 2006 (UTC)

I saw these paragraphs in the German Wiki ():

• Echt lebendgebärende Arten finden sich in beiden Familien, besonders in tropischen Regionen mit einem über das Jahr hinweg stabilen Klima und gleichmäßigem Nahrungsangebot. Die sich aus den nur mikrometergroßen Eiern entwickelnden Embryonen werden im Uterus von ihrer Mutter ernährt; sie werden daher als matrotroph bezeichnet. Die Versorgung erfolgt entweder durch mütterliche Sekretabgabe in den Uterus oder durch eine echte Gewebeverbindung zwischen dem Gebärmutterepithel und dem heranwachsenden Embryo, eine so genannte Plazenta. Ersteres kommt nur außerhalb des amerikanischen Kontinents vor, letzteres findet sich in erster Linie in Amerika und der Karibik, seltener in der alten Welt. Die Tragzeit, an deren Ende die Jungtiere bereits weitgehend entwickelt geboren werden, kann bis zu 15 Monate betragen. Die im Uterus eines Weibchens vorfindlichen Embryonen müssen nicht notwendigerweise gleichaltrig sein; es kann durchaus vorkommen, dass sich dort zahlreiche unterschiedlich entwickelte Tiere finden, die zudem von verschiedenen Männchen abstammen.

• Die Peripatopsidae weisen verhältnismäßig viele als ursprünglich oder "primitiv" eingeschätzte Merkmale auf. Sie besitzen 13 bis 25 Beinpaare; hinter oder zwischen dem letzten davon befindet sich die Geschlechtsöffnung (Gonopore). Sowohl eierlegende (ovipare), eierlebendgebärende (ovovivipare) als auch echt lebendgebärende (vivipare) Arten kommen vor, eine Plazenta besitzen Peripatopsidae allerdings grundsätzlich nicht. Ihr Verbreitungsgebiet liegt zirkumaustral in Australien und Tasmanien, Neuseeland, Neu-Guinea, Südafrika und Chile.

• Die Peripatidae zeigen eine Reihe von abgeleiteten Merkmalen. Von größerer Durchschnittslänge als die Peripatopsidae besitzen sie auch mehr Beinpaare: Deren Zahl variiert innerhalb der Gruppe zwischen 22 und 43; die Gonopore liegt immer zwischen dem vorletzten davon. Ovipare Arten gibt es bei den Peripatidae nicht, die weitaus überwiegende Anzahl ist vivipar. Bei vielen Weibchen der letzteren Gruppe bildet sich eine Plazenta aus, die den heranwachsenden Embryo mit Nährstoffen versorgt. Vorkommen der Peripatidae sind auf die tropische und subtropische Zone beschränkt; im Einzelnen kommen sie in Mittel- und im nördlichen Südamerika sowie auf mehreren karibischen Inseln vor, daneben auch in Westafrika, Nordindien, Malaysia und einzelnen indonesischen Inseln.

Sorry, my German is not that good. -- Toytoy 12:42, 13 March 2006 (UTC)

No class or order?

Have a class and order been named for the phylum's taxonomy? If not, why not? Aren't order and class standard ranks that are always added? The phylum Placozoa has only one family with one species, but they still made an order and class for it. So where are these for Onychophora? Jerkov 17:29, 26 July 2006 (UTC)

Translation still in progress

As noted above, I've been working intermittently on a translation of the Featured Article on this subject from the German Wikipedia. I've got a bit more done of late and my progress so far can be seen in my sandbox. I'm going to hold off merging it until it's completed, but any wikifying etc. that people might feel like doing while it's still in the sandbox would be very welcome. Once again, sorry for the long drag - I'll get there eventually, honest! --YFB ¿ 02:33, 9 August 2007 (UTC)

I've wikified the classification section as best I could, replacing the Latin taxon names with the usual English ones, and assumed the dagger meant the taxon was extinct. (I haven't bothered doing it for subtaxa since that's kind of implicit :) And wow, Peripatopsidae has a lot of genera!) Hairy Dude 00:34, 16 September 2007 (UTC)

How about a line drawing?

Thanks for the picture, but how about a labeled line drawing of the beastie? I'm having trouble envisioning its segmented head. The Sanity Inspector 18:57, 9 November 2007 (UTC)

Translation Complete!

I've finally finished the translation from the German "exzellentes Artikel" that I've been tackling on-and-off since May last year. I've tried to make it as literal a translation as possible but have made adjustments where necessary to make the English more natural. There are probably quite a few errors so corrections are welcome! Cheers, --YFB ¿ 19:12, 1 March 2008 (UTC)

Thanks, it's much better than before! It does need some tweaking though, especially about the annelid/arthropod relationships. When I get the time I'll go through and edit it for those things and grammar. KarlM (talk) 15:43, 2 March 2008 (UTC)

Great, look forward to seeing your edits. The phylogeny and taxonomy sections were a bit beyond my level of expertise so I'm pretty sure I've used the wrong terms in places. Thanks, --YFB ¿ 18:10, 2 March 2008 (UTC)

Segmented?

Here's an excerpt from Stephen Jay Gould's essay The Reversal of Hallucigenia:

About eighty species of living onychophorans have been described...

...They are elongated, soft bodied, and unsegmented (the ringlike "annulations" on antennae, legs, and sometimes on the trunk are superficial and do not indicate the presence of segments, or true divisions of the body).

--Roivas (talk) 21:43, 8 May 2008 (UTC)

Examples?

Would this overview article on the phylum be improved by two or three brief examples of named species? I'm thinking of largest, smallest, most widely-distributed, and the most frequently-encountered as exotic pets: there's no need for more than a sentence each, with a link to a stub article (or a real one if they exist) for the named species.

Nile (talk) 22:52, 20 April 2009 (UTC)

Pigmentation

Just a note I need to elaborate on when I get the chance to source it - http://www.biologia.ucr.ac.cr/rbt/attachments/onicof/onynew99/onyevolu.htm

http://download.interscience.wiley.com/cgi-bin/fulltext?ID=119239364&PLACEBO=IE.pdf&mode=pdf

Martin (Smith609 – Talk) 22:28, 12 May 2009 (UTC)

Eyes

The section on sensory organs mentions the eyes which is not coming from the German article most of the rest is coming from. It says:

The rhabdomeric eyes of the onychophora are thought to be homologous with the median ocelli of arthropods; this would imply that the last common ancestor of arthropods bore only median ocelli.[3] However, the innervation shows that the homology is limited: the eyes of onychophora form behind the antenna, whereas the opposite is true in arthropods.[4]

This seems both NPOV and flawed to me, for the following reasons:

1) "this would imply" is a counterfactual, i.e. it would but it doesn't. However, the link is to an abstract of a scientific paper that actually makes that claim, and since Wikipedia must remain NPOV, either this is a valid scientific claim (in which case it should be refrased to something like "scientists have claimed that ..."), or it isn't, in which case I'd like to see more than one dismissals of it. Which brings me to

2) the "however" part which dismisses the idea brought forth in 1) is referenced only by an ISDN number, one that I haven't been able to trace, with no description or title or whatever. This doesn't seem to me a very valid rebuttal. And even if it is, has it more value than the other source? Also

3) "the homology is limited: (...) behind the antenna, whereas the opposite (...) in arthropods". However, this claim is only valid when the antenna of the velvet worms and arthropods are homologous, which this article claims it isn't. I quote:

[The velvet worm antenna] probably do not correspond directly to the antennae of the Arthropoda, but perhaps rather with their "lips" or labrum

If this is true, the homology of the eyes is still very much possible, as the labrum in arhtropods are below the eyes.

Perhaps someone can shed a light on what is true and what is not, as I am unfortunately no expert on matters.

One more remark: the text mentions the eyes are "just underneath the head". I think what's meant is that they are just below the skin of the head. I'm not entirely sure, the original German text doesn't seem to mention it.

Jalwikip (talk) 10:18, 12 June 2009 (UTC)

Hallucigenia?

It seems that everybody is now looking at the pre-Cambrian animal hallucegenia as a form of onychophora. I'm no expert, so what do people think of this development! 124.170.123.65 (talk) 06:35, 29 September 2009 (UTC)

It's been pretty well established for some time. The depiction in Wonderful Life is upside down. KarlM (talk) 08:13, 29 September 2009 (UTC)

Details

What texture is the body (ie slimy, soft, hard, etc)? It mentions that they have slime glands, but not very much else on this topic. UNIT A4B1 (talk) 22:30, 9 March 2010 (UTC)

False information

Apparently I have to write here to show a very common mistake:
"The segmented worm-like organisms"
They are not worm-like at all, anything but a worm.
Calling it a worm is like calling a caterpillar a worm - so unless any proof can be shown that it is indeed, a worm - it will be deleted.
They have cuticle, something a worm does not have.
They have 'legs', something a worm does not have.
Others example follows.
—Preceding unsigned comment added by 204.112.133.48 (talk) 03:01, 10 May 2010 (UTC)

I think the point of that is to give the reader a general idea of what velvet worms are like. How about "caterpillar-like"? ~XarBioGeek ^(talk) 21:19, 10 May 2010 (UTC)

A velvet 'worm' is much more similar (anatomically and physiologically) to a caterpillar then to a worm. I would whole-heartedly agree to this. —Preceding unsigned comment added by 204.112.133.48 (talk) 23:06, 10 May 2010 (UTC)

They are often compared to worms, caterpillars and slugs, e.g. "Onchyophorans, or velvet worms, are ... wormlike bilaterians ... Because they resemble worms with legs ... Superficially they resemble caterpillars, but have also been compared with slugs" (my underlining) Ruppert, Fox & Barnes, Invertebrate Zoology, 7th edition, p.505. Peter coxhead (talk) 14:56, 21 January 2011 (UTC)

Not sure what to do or when I can do it, but...

I find the article to be incoherent in places and with some curious claims. I am not an expert on the Onychophora and the article is long, so I am not willing to undertake to edit it in case other commitments hit the fan or my memory simply lets me and everyone else down. Besides, I have very little literature on onychophora at my disposal. Life is so sad. However, I shall try to remember to do what I can as soon and as well as I can. And as coherently. Meanwhile, I hope that this inspires any well-informed and sympathetic parties to see what they can do in the mean time. JonRichfield (talk) 19:12, 19 July 2014 (UTC)

Why does "Protracheata" redirect here?

Not mentioned in article. 86.179.191.90 (talk) 01:57, 8 February 2015 (UTC)

Where the word "bear" is used is meant "water bear"?

I think a word may have been omitted.Jrm2007 (talk) 01:54, 21 March 2015 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Onychophora/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

Comment(s)

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== recapitulation is wrong == "The similarity of these creatures to caterpillars is not purely coincidental; as with most creatures, the larval stage of moths and butterflies are thought to represent, however inconsistently, previous evolutionary stages." The idea that ontogeny recapitulates phylogeny was debunked about a century ago - see Recapitulation_theory. For example, human foetuses don't develop gill slits because fish had gills, they do so because fish foetuses also developed gill slits. Nature is often conservative, not changing this pattern of development as no need to. There is no doubt that velvet worms are related to arthropods in some way, but I don't know of any evidence that they are specifically related to caterpillars. You could make a comparison with adult centipedes by way of analogy, but this doesn't necessarily imply a direct evolutionary relationship. When comparing animals for common features it is easy to see similarities that result from convergent evolution. For example, koala bears have opposable thumbs like us. But there is no close relationship - they are marsupials. The similarity is because they are adapted for tree climbing as are we. --J987 21:19, 22 October 2007 (UTC)

Substituted at 21:54, 26 June 2016 (UTC)

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Paragraphs which may need splitting

The sections "[s]kin and muscle" (first paragraph), "[c]irculation", "[f]eeding" (both paragraphs), and "[r]eproduction and life cycle" (first paragraph) all have paragraphs that I think need splitting. Could someone please tell me where I should split them?--Thylacine24 (talk) 02:59, 25 December 2021 (UTC)