CIAC 2006 powerpoint and Finned Octopoda article

monty

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tonmo said:
1) Jean McKinnon's CIAC 2006 Powerpoint Presentation (2 meg .ppt file) has been added to our Ceph Science articles.

Any chance this can be posted as the .ppt file or a real web hierarchy? The .mht version appears to need internet explorer (or at least is completely inaccessable under amd64 linux firefox), which I don't have handy... If it's a pain, I can go read it on a windows machine, but I figured I'd mention it in an effort to make TONMO content accessible to people of all operating system creeds...
 

Euprymna

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Hi Jean,

cool slideshow, wish I could have been in Hobart to hear your presentation! But a bit too far for me!

Having read your presentation I was wondering what was the reason that you used calcein? Was it just for staining? Could you explain me that quickly? In your slideshow you did not mention after how long you removed the statolith after staining them? was it after 24 hours to validate a daily deposition?
Here we are trying to validate growth rings in Ovulgaris beaks, stained them with tetracycline. however, it appears that merely 20% of those beaks are easily readable. Some of them are really clearly showing bands (daily???) but some are very bad!
cheers,
eups
 

Euprymna

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main_board said:
Out of curiosity, how old are the octos you are aging?

Cheers!

Hi MB,

Well I don't really know!! That's the problem...
For our O.vulgaris, we've got about four different weight classes of individuals ranging from 150 g to 1 kg. They were captured so we don't know their age and cannot infer much because size is not a good measure of age in cephs. For now, I can only guess that the largest are about 7-8 months old but maybe they are younger and it could be that the smaller ones are older...

eups
 

Jean

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Euprymna said:
Having read your presentation I was wondering what was the reason that you used calcein? Was it just for staining? Could you explain me that quickly? In your slideshow you did not mention after how long you removed the statolith after staining them? was it after 24 hours to validate a daily deposition?
Here we are trying to validate growth rings in Ovulgaris beaks, stained them with tetracycline. however, it appears that merely 20% of those beaks are easily readable. Some of them are really clearly showing bands (daily???) but some are very bad!
cheers,
eups


Hi Eups,
I was using calcein just for staining for several reasons

1) I had it on hand :biggrin2:
2) I find that TC has toxicity problems (it is after all an antibiotic)
3) TC oxidises rapidly and after a while the slides loose the mark (unless you store them wrapped in tinfoil or immersed in glycerin). I have slides made over 10 years ago of bivalve shell sections which still have very clear calcein rings.

Hope this helps

J
 
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Ok, I was way off. I was just curious as there was a presentation at CIAC regarding aging via beak increments as well. However, I believe they were working with upper beaks from ommastrephid squid paralarva. It was pretty cool because they got a one increment per day rate of growth for the beaks as well. Anyways, I don't really know where I was/am going with this...good luck with your beak work.

Cheers!
 

Euprymna

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main_board said:
Ok, I was way off. I was just curious as there was a presentation at CIAC regarding aging via beak increments as well. However, I believe they were working with upper beaks from ommastrephid squid paralarva. It was pretty cool because they got a one increment per day rate of growth for the beaks as well. Anyways, I don't really know where I was/am going with this...good luck with your beak work.

Cheers!

Thanks MB,
It appears also that O.vulgaris lay down daily rings on their beaks, the upper one being the most easily read. However, the problem lies in the techniques of beak prep. In only a few these increments are easily countable.

eups
 

Euprymna

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Jean said:
Hi Eups,
I was using calcein just for staining for several reasons

1) I had it on hand :biggrin2:
2) I find that TC has toxicity problems (it is after all an antibiotic)
3) TC oxidises rapidly and after a while the slides loose the mark (unless you store them wrapped in tinfoil or immersed in glycerin). I have slides made over 10 years ago of bivalve shell sections which still have very clear calcein rings.

Hope this helps

J

Thanks for this Jean,

you're right about the toxicity problem of TC but since we do not bath the octo in the solution but rather deliver it orally (with low cc), I think this shouldn't be an issue. However, we all know that antibiotics should be used with caution!
We have just started this and haven't seen the resulting beaks so do not know the strength of the staining. For finfish otoliths it works fine but for cephs??? we'll have the pleasure to see that in a while...

thanks,

eups
 

monty

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I've always wondered what the mechanism is for there being a daily change in ceph beaks/statoliths/... causing the rings. In a tree, it makes sense that there are seasonal changes that show up in the growth patterns, and I could even buy daily changes in fast-growing plants in that the new material is different depending on whether light or dark photosynthesis is happening or based on temperature or something.

I can maybe imagine that in shore and shallow water cephs, they can see the sunlight, but I don't understand why that would change the biochemistry of how they grow their statoliths. I guess it's plausible that an octopus might grow more when it's hiding in its den than when it's out and about actively hunting, and perhaps that might be extended to squids actively hunting versus lazily swimming. However, for deep sea cephs, I wonder how they even know what time of day it is, anyway-- it's dark and pretty much uniformly cold once you get below a few hundred meters or so, right? I know Humboldts and Nautilus have vertical migration from day to night, but aren't these rings present even in cephs that never get close enough to the surface to tell from light what time it is?

As I'm typing, I'm wondering if awareness of daytime is an evolutionary throwback, since I've read that it's believed that cephs evolved near the shore but many were driven to the depths by modern predators...

It's also pretty interesting that the growth curves appear to be so different in male and females; it'll be interesting to see how broadly this applies...
 

Jean

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There is a theory that it has to do with tides! That somehow these animals can detect the comparatively minute changes in water pressure!

J
 

monty

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Jean said:
There is a theory that it has to do with tides! That somehow these animals can detect the comparatively minute changes in water pressure!

J

Wow, I didn't think of that possibility at all... if they can sense pressure at that level of detail, I wonder if that's part of the reason a lot of open-water and deep-dwelling cephs don't do well in tanks... they'd be constantly acutely aware that they're less than ten feet deep! Of course, nautilus in tanks seem to deal with it ok, and they clearly have a need to be aware of pressure through the chamber control system... I know that in the wild they have vertical migrations over the day, but I don't know if they just stop doing that in a tank. I thought I read in some "pop science" place a number of years ago that when a nautilus is brought up to be put in a tank, the pressure changes cause some irreversible damage such that it can't go to its natural depth any more... I suspect this was wrong, since I've never heard it from anywhere credible, though.

It's hard to imagine how the pressure/tidal stuff would work for a deep sea midwater ceph, though-- although there would be some pressure changes from the tides, I'd think they'd be dwarfed by the animal's depth changes, and how would it be able to maintain a constant depth or know what depth it was at without using the pressure itself as the guide? Hmmmm, all very mysterious....
 
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