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16:48 10-06-2012
Jan
I found one problem interesting to speculative biologists. We have some discussion if bats fly more efficiently than birds. It seems that scientists do not agree on this, but there is common agreement that bats and birds fly very differently from each other. One of the differences is the ability of birds to separate primaries from each other during upstroke:
"As the wings carry out their upside-down backstroke, the primary feathers twist in their sockets and separate from each other like the panes of a venetian blind. This motion allows air to flow rapidly between the feathers. The upside-down primaries are held at a slightly upraised angle, creating an increased angle of attack for each of the primary feathers and generating a small amount of lift during the backstroke. The separated feathers also cause much less drag."
http://books.google.cz/books?id=LmBdO2XGB-8C&printsec=frontcover&hl=cs#v=onepage&q&f=false

If I understand it correctly, it decrease the birds´ability to hoover, but increase the efficiency of their flight. The flying animals in Avatar can do the same and this is one reason I think they much more interesting than any other animals in the movie. Their design is original and well thought through and there is nothing redundant about it. But it would be interesting to know if it is possible to go one step further to an animal whose design would take the venetian blind inspiration more literally and possibly effectively, for example tying slats along their lenght or orient them in different direction. After all, for some reason birds never exceded the size of largest pterosaurs and the basic design of their wings had originally nothing to do with flight.
14:01 10-06-2012
Jan
Btw, can we know more about the strange animals in the last article?
20:23 05-06-2012
Jan
Thank you. No matter how the joint in millibede trunk works, there is obviously many possibilies and it is hard to say which one is better. Look at these mechanical designs, just for example http://www.anthrobot.com/omni-wrist-v/, http://selenianboondocks.com/2010/06/cjoint1/ etc.
I think that it would be more interesting to create a skeleton which has no central spine, but uses various joints between different bones to allow maximum flexibility and protection at the same time. I have seen something similar on speculative evolution forum, but cannot find it again.
03:18 05-06-2012
Drás Researcher
Jan & SN: I don't know if this will help you with millipede joint segments, but I thought it looked like it might help!

http://lanwebs.lander.edu/faculty/rsfox/invertebrates/pachydesmus.html
12:22 04-06-2012
SN
Jan 1: thank you. Your remark about the spinal cord is interesting. In vertebrates the spinal column evolved out of a sort of rod (the notochord) running parallel to the spinal cord. Later the vertebral column enveloped the spinal cord. I do not know whether this was because of the benefit provided by protecting it, or because of a problem in dealing with two structures in the midline in one another's way. Note that the aorta and vena cava are not in the median plane and are not protected by vertebrae, while harming them will kill faster than a spinal cord lesion. In short: the spinal cord(s) do not need to lie near the vertebral column.

Jan 2: well, the blobs in the 'central column' are spherical for a reason: they allow for rotations in three directions.

Jan 3: As for joints in arthropods, I have also searched in vain. If you get hold of a crab's claw, the joints are perfectly visible. There is otherwise remarkably little information on things such as how millipedes allow movements along body segments in three directions.
11:12 28-05-2012
Jan
"Millipedes... The cuticle of each segment is composed of a markedly domed upper shield or tergite, together with two smaller side plates and a sternite on the lower surface... Each millipeed tergite slightly overlaps the one behind it, and there is a simple ball and socket joint between neighbouring rings."
http://www.the-piedpiper.co.uk/th11b.htm

But they do not say where the joint is
11:07 28-05-2012
Jan
Perhaps the simpliest solution to long flexible body would be something similar to large universal joints, like of this snake robot http://robotics.caltech.edu/pictures/hardware/spatial.snake.gif Innervation would need to be different, though
10:40 27-05-2012
Jan
The new posts about rusps are amazing. The question of vertebral column is interesting, btw, I think that there is also the possibility of making it in zigzag fashion (for example, left-right-left-right or ventral-dorsal-ventral-dorsal...) for greater flexibity. The problem of the protection for spinal cord would need other solution, though.
16:45 25-05-2012
SN
Shelley: it is. Haven't I received your message before? I remember replying that I would be interested if these watercolours concern the rhinogradentia themselves.

We can continue the conversation using nastrazzurroATgmail.com (please replace AT with the @ symbol).
20:52 24-05-2012
Shelley Reed
Is this Sigmund Nastrazzurro's site? If so, I just stumbled across your Rhinogradentia II post from 10 July, 2008 about Dr. Gerolf Steiner. I have several original watercolors of his that my father bought from him in Germany in 1946. I'm trying to find out what their value might be. Might you be able to help? Many thanks, Shelley
22:47 15-05-2012
Pete
@Gabriel - Wow! That looks great! =) More complicated than I thought though... =D
21:48 15-05-2012
Gabriel
A better design posted instead (Original deleted)
http://sketchup.google.com/3dwarehouse/details?mid=342ab5cabe2a32a497eab34d9487fc23&prevstart=0
The segmented ring looks more efficient because segments can achieve the desired angle at each step in the cycle.
16:15 13-05-2012
Gabriel
I managed to draw a Google-Sketchup illustration. If you access the 3D warehouse, it is named "ring-shaped object moving in water" and has a narrative as well.
Sketchup is not exactly suited to handle realistic behavior of bending objects, so I had to manually tackle some of the broken lines created. You will notice the surface is too bumpy and bends are slightly asymmetric, but to view it, keep the camera located in the same position I saved file with. The flat ring on the left is the position at rest, the sequence is from left to right, then the flat ring on the right is the final position at rest, after one cycle.
14:36 13-05-2012
SN
Pete: sorry for having made you wait. I do not know whether or not the Festo/Thomastapir structure is one of many similar structures. The video you supplied shows that more than one is possible, but whether it can be generalised I do not know.

Gabriel: your first solution is one I also envisaged. I think I understand what the Möbius one would look like, but a drawing would definitely help explain how it works...
00:49 13-05-2012
Pete
Thank you Gabriel!
Oh, I'm sad to hear about Nereus... =(
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