Amazing new research: nautilus embryology and development

[monty]

http://scienceblogs.com/pharyngula/2007/07/cephalopod_development_and_evo.php

The article can be found here if you have institutional access:
http://www3.interscience.wiley.com/cgi-bin/jissue/109771912

The implications of this work for cephalopod genetics, palaeontology, development, classification, and so forth seem to be about the most substantial I've seen in the past 20 years, although maybe I'm just biased because I'm easily excited by the link between genetics and body plans.

I need to read both the Pharyngula post and the article in more detail, and I must confess that I'll need to do a lot of support reading, particularly regarding some of the homologies to non-ceph molluscs-- perhaps some of you real marine biologists with a broader knowledge of mollusc anatomy can help an ignorant computer scientist out here?

As usual, my understanding of "fair use" is that I can email the PDF of the paper to individuals for educational use, let me know if you want it.

This is the first paper I've wanted to "cross-post" to the Physiology, Fossils, and Nautiloidea just to make sure all the people I'd love to hear chime in on it actually see it, but for now I'll assume most of the fossils people will see it here....

 

[mucktopus]

very very cool.

 

[cuttlegirl]

Ohhh, this is sooo cool. Monty, I would love a PDF copy of the article. Very interesting stuff, can't wait to read the article...

 

[Architeuthoceras]

Everyone wants to make anterior ventral

 

[cuttlegirl]

I finally finished reading the article. Some parts I do understand (mostly all the embryology parts). I had to reread some parts... especially the brain development section. I have lots more questions (of course ) and wish I could ask the author's some of them...

The most interesting part (to me) was tentacle and arm development. When I have a little more time (8 relatives visiting at the same time right now), I will go into some more detail.

In coleoid (and Nautilus) embryos, there are 9-10 buds on each side of the embryo that develop into the arms and tentacles. During development, some of these buds fuse and become the arms and tentacles.

It reminded me that there are some deformities seen in octopus and cuttlefish where their arms branch.

See here...
Octopus with branching arms

Maybe these deformities are caused when the buds fail to fuse completely?

I also remember there was a member who studied S. officinalis, who had photos of juvenile cuttlefish with branching arms. I just can't remember his name... He was also an artist who painted the inside of this bathroom with cephalopods. I think he was from Germany... time to Google...

Found it...
http://www.kawolfram.de/cuttlefish/newversion/menu.html

Click on Juvenile cuttlefish and then special: little mutants.

 

[Tintenfisch]

I just can't remember his name... He was also an artist who painted the inside of this bathroom with cephalopods. I think he was from Germany... time to Google...

She Her TONMO handle is Tigerkatze_82. Name is Katja I think?

Thanks for re-posting that thread. I went back and re-attached the branching arms image. I wonder if this occurs sometimes following trauma, when the arms are re-growing. I found a few very interesting instances of what looked like regeneration gone awry while I was overseas - see attached. This is an arm from a M. robusta specimen. The arm tip was regrowing (on this and several other arms, and one tentacle was regenerating), and in the middle of the arm, this odd finger-like projection with about 70 closely set suckers was also sprouting. Would have been very interesting to see what it turned into, given the chance to fully regenerate. The stubby projection is about 1.5 cm long.

 

[monty]

I hadn't even thought about the branching arms stuff, but you're right, it seems very relevant... these posts also have made me realize that I don't know a fundamental aspect of how arms grow initially and regenerate: do they grow from the base, or from the tip? My educated guess is that they'd be more likely to grow at the tip, since all the nerves and musculature could be preserved down at the base more or less intact, and because I've never seen any evidence of new sucker formation down at the base, and because if they lost half the arm, it would make sense to be able to replace the tip...

I also wonder if an octo with branched arms loses one, if it grows back normal or branched, and if it loses just a branch, does it grow a new single or double branch above the cut?

I've been re-reading the paper and following some references, I still think it's quite interesting stuff... more to come on that front.

And as a side note, I for whatever reason had thought Tigerkatze was male, too, although I don't think I had any reason to... it's kind of a neat thing that in many cases on TONMO and on the net in general, people can express their thoughts without a danger of it being tied to gender/race/disability/phylum/... although I suppose it also has the side effect that it hides diversity, too. I realized after the fact that I had made the "fingerscrossed" icon as my own skin color without really thinking that most of our smilies are yellow...

I'm finding I need to learn a lot of terminology to plumb the depths of this research, since I'm not too up on embryology or some of the detailed taxonomic terms... like the difference between ontogeny and phylogeny, what exactly anlagen means, archetype vs phylotype (wikipedia wasn't really clear on what this distinction is, can anyone help me out with that one? edit: this wins my award for "least helpful definition ever") Anyone who knows a bunch about gene expressions in non-ceph molluscs could help me out a bit; I don't know where engrailed or distalless are expressed most animals (I've only heard about them in fruit flies and vertebrates, and I'd have to look them up even for them...)

I'm still astounded by the implications of the relationship between gastropods, ancestral cephs, and modern nautilus vs. coleoids... it looks like the first cephs can be reconstructed as having 5 pairs of arm buds from the foot on each side, maybe?

Although they didn't refer to this in the paper, having just read Ward's theories about oxygen-driven evolution, I think that the funnel's origin from right next to the gills seems to potentially add support for the idea that the first ceph evolved the ability to squirt large volumes of water past the gills to be active in low-oxygen water, then the jet allowed them to start swimming, and the rest of ceph-ness came from the ability to be a swimming rather than crawling/sessile creature.

I'm off to San Diego for a computer graphics conference though, so I'm not sure I'll have time to read more on this until next week...

 

[tonmo]

Great posts all -- I just rated this thread accordingly!

 

[cuttlegirl]

Anlagen is plural for anlage. Anlage (in embryology) means the precursor for that organ.

 

[DWhatley]

Does it strike anyone as odd that the budding is described as originally in two sets of five? I find that interesting not only because of our own digits but because neither 5 nor 10 are typical numbers used as a base outside human everyday math (and that is probably because of our fingers). In the computer world 2, 8 and 16 are the more common bases. I was not a math major and have limited math education but it always bothered me that pi could never be calculated and irrational numbers exist as special case handling. This uneducated quandry has always made me believe that 10 was an inappropriate base and that we were missing something important in the basic definition of our math system. It just doesn't seem right that you cannot exactly calculate the surface area of the tangible, common circle. The octopus having 8 arms seemed to suggest something significant but now, maybe not.

 

[DWhatley]

Tintenfisch,
I wonder if imperfect regeneration is not more the norm than the oddity, particularly if there is any kind of venom involved. Our dog was bitten by either a snake or a spider (vet could not determine but felt it was probably a brown recluse since there was only one puncture wound). After sluffing off the contaminated tissue, not only did the leg regenerate somewhat oddly, the dog developed odd growths in other areas of the leg. The growths and the now misshapen leg have not caused the dog problems and she has already lived a "normal" lifespan for the breed but her body went into overdrive trying to heal the wound and seemed to over produce the replacement parts.

 

[erich orser]

This is a return to one of Tintenfisch's lighter mentions, but personally, I always knew that the two of you were female. In your case, Kat, I think I already knew that (seen your photo on the website. Hard to mistake that). In Tiger's case, I just assumed. Not that this means a darn thing, but just thought I ought to mention. 'Cause I'm housesitting (catsitting) for Sorseress and am bored. I hope to contribute soon. I sorta suck, but I'm writing fictional stuff. Got zero extra time. Especially with second drafts. Wanna make the money, yo.

 

[monty]

This is a return to one of Tintenfisch's lighter mentions, but personally, I always knew that the two of you were female. In your case, Kat, I think I already knew that (seen your photo on the website. Hard to mistake that). In Tiger's case, I just assumed. Not that this means a darn thing, but just thought I ought to mention. 'Cause I'm housesitting (catsitting) for Sorseress and am bored. I hope to contribute soon. I sorta suck, but I'm writing fictional stuff. Got zero extra time. Especially with second drafts. Wanna make the money, yo.

I wonder what cues people use to guess gender from internet posts... whatever they are, I'm pretty sure I'm not as good at picking them up as a lot of people, but that may be a good thing... I was rather horrified that some study showed that there was an anti-female-name bias in academic peer review, where the same paper submitted as "J. Doe" or "John Doe" did better than "Jane Doe." I'm glad the main Computer Graphics conference does anonymous peer review so that's not an issue, but it's still weird and very disturbing. This study (PDF)
suggests that there was not evidence of bias in 2001 for some unspecified journals, but that there are reasons to be concerned about this kind of stuff.

 

[Nancy]

It's not so hard to guess gender and age. Because of the advice I give to would-be ceph keepers, I've become very good at watching for clues. For instance, a person might refer to "my girlfriend" or "my mom". There are clues in the writing styles and vocabulary and sometimes the choice of avatar which can hint at age and gender. Interesting that some people also show up on other websites where their profile gives a lot more information than there. Not that such things matter very much, but it's nice to know your audience as well as possible.

Nancy

 

[monty]

Yeah, I notice the age cues pretty readily, but I don't get the gender ones too often... for example, I don't think I've seen any reason to assign a gender to Robyn in the public TONMO posts (although when I was googling for info on her woods hole project I figured it out, but that was after she'd been posting for months.) I may well have missed cues, and insofar as I'd thought about it I suspect she might be female (although, also, why I should need/want to know is another question; I'm not planning on ask her on a date). I think in the case of Tigerkatze, I think I unconsciously associate "Tiger" and "German" with "people who like talking about WW2 tanks" who appear to be predominantly male for some reason That probably shows a silly bias on my part, so mea culpa lest "Tank Girl" show up to teach me a lesson (and anyway, a lot of my friends are women who are flattered to be compared to Ripley in Alien.)