CIAC 2006 powerpoint and Finned Octopoda article

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...
 

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....
 

Euprymna

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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
I didn't knew that! but for intertidal burrowing bivalves such as cockles, a transversal cut through the shell reveals tidal bands associated with reduced growth when the tide is out and thus cease filter feeding. So they show more than 1 band a day and show two small band and 2 larger ones a day. It is also possible to determine bands caused by disturbance such as when dredges hit them which sometimes confuses the band counting for age determination!

It is interesting to note that down at deep sea hydrothermal vents, there are strong tidal periodicity in the outflow of hydrothermal fluid. This is because the difference in pressure caused by the tide affects the oceanic crust. This cycle of fluid emmanation in turn may affect the activity of the animals, who cease their activity when the flow is high thus more toxic.

I guess that for cephalopods the daily growth rings in beaks and statoliths are associated with their activity cycle and considering their fast growth rates, these should be more evident than in slow growing fish or bivalves. But do not know more...worth exporing!

As for deep and midwater cephs that do not perform vertical migrations, maybe they developed a daily activity rhythm due to their prey's vert migration? Or as Monty said, the daily activity rhythm is a shallow water ceph trait that was somehow not detrimental (even beneficial?) and thus kept in those cephs that colonised deep waters...I THINK it has been suggested for some deep water animals but which?? don't remember now...




eups
 

Jean

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Euprymna said:
I didn't knew that! but for intertidal burrowing bivalves such as cockles, a transversal cut through the shell reveals tidal bands associated with reduced growth when the tide is out and thus cease filter feeding. So they show more than 1 band a day and show two small band and 2 larger ones a day. It is also possible to determine bands caused by disturbance such as when dredges hit them which sometimes confuses the band counting for age determination!
That was what my MSc thesis was about!!!! I worked with a local venerid clam Austrovenus stutchburyi and validated that macro increments were annual (with calcein :biggrin2:) and micro were tidal, I could even spot spring and neap tides. Could also see spawning and storm interruptions in growth...........plus the landslide that fell on my cages!!!!!

J
 

tonmo

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Jean has submitted another powerpoint file for our enjoyment --

Seaweek2006.ppt - 2 megs

Per Jean: "I have a new powerpoint presentation for you! We have just completed "Seaweek" which is a Marine Education/Awareness week and as part of it a few grad students were asked to give a short presentation on their research and why they do it!"

Thanks Jean!!
 

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