Foot of a jumping spider

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rjlittlefield
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Foot of a jumping spider

Post by rjlittlefield »

Image

The feet of a jumping spider are covered with lots and lots of hairs, organized as numerous larger hairs each tipped with a tuft of much finer hairs called "setules". The setules are attracted to solid surfaces by very short-range van der Waals forces that can be broken and re-established an indefinite number of times without weakening. Individually, the attractive forces are tiny, but summed over the huge number of them, the aggregate force can be 170 times the weight of the spider! At least, that's what these articles say: "Spiders make best ever Post-it notes" and "Spiders get a grip".

An optical image like I've posted here doesn't have enough resolution to show the individual setules, but I believe the tufts of them can be seen as fuzzy gray blobs at the ends of the black hairs.

Another interesting feature visible in this image is some "beading" visible on many of the long sensory hairs. At first I thought this might be an artifact of the stacking procedure. But the beading is present even in individual frames, so I think it's real. What is its significance, I have no idea.

It's the usual situation -- get close, get questions. Extreme close-ups are seldom boring! :D

--Rik
Canon 300D, 10X NA 0.25 achromat on 180mm extension, stacked by Helicon Focus at 0.00025 inch. Cropped to about one half frame width, shown here at about 200X.
The web page linked above references an article published 19 April 2004 in the Institute of Physics journal Smart Materials and Structures).
More info and additional pictures can be found by visiting http://www.iop.org/ and searching for "setules".

MacroLuv
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Post by MacroLuv »

Wow! Great. :shock: I think Gecko lizards uses van der Waals forces too. :D
The meaning of beauty is in sharing with others.

P.S.
Noticing of my "a" and "the" and other grammar
errors are welcome. :D

rjlittlefield
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Post by rjlittlefield »

MacroLuv wrote:I think Gecko lizards uses van der Waals forces too. :D
Yep, that's mentioned in one of the articles I linked.

--Rik

DaveW
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Post by DaveW »

Got a good set of claws too!

DaveW

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Post by rjlittlefield »

DaveW wrote:Got a good set of claws too!
Indeed, and I notice they're kind of retractable. Depending on position of the leg and I don't know what else, the claws can extend way beyond the pad of hairs as shown above, or hide completely behind it.

Come to think of it, I guess that makes a lot of sense. Sometimes the spider needs to use the hairs for adhesion to some surface, and it would not be good if many of the hairs were held away from the surface by the claws. But when the claws are needed, they'll work a lot better if they stick out beyond those really pretty stiff hairs. Very clever, the way these critters are put together!

--Rik

Ken Ramos
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Post by Ken Ramos »

Rik said:
Very clever, the way these critters are put together!
...but oh so easy to dismantle them! :twisted:

Quite an interesting post here Rik. It is fascinating though how they are constructed. Excellent photograph even though you could not resolve those van der Waals forces very well and I don't imagine I will be using them as post-it notes anytime soon. I wonder who names these anatomical parts anyway. :-k

beetleman
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Post by beetleman »

Wonderful photo Rik. Very nice detail. I have read about the geckos but did not know the spiders did the same thing :shock: (I think your stack is better than the SEM picture in the article :wink: )
Take Nothing but Pictures--Leave Nothing but Footprints.
Doug Breda

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Post by rjlittlefield »

beetleman wrote:Very nice detail. I have read about the geckos but did not know the spiders did the same thing :shock: (I think your stack is better than the SEM picture in the article :wink: )
Well, of course I just couldn't resist trying to get even closer.

Canon 300D, 20X NA 0.40 achromat on 150mm extension, cropped and resized to 80% of "actual pixels". Stacked at 0.0002 inch.
Image

I'd be a bit surprised if this is resolving individual setules, which are described as "just hundreds of nanometres in width". Maybe they clump together -- I know that this beast had its feet wet and did not get a chance to clean them before posing. Or maybe this kind of spider has bigger setules. An SEM could tell us... :wink:

But at least now we can see that those blobby ends are actually spatulate and that the gray stuff has some interesting texture.

We can also see that a bunch of the larger hairs are feathered. I'm not sure whether this explains the "beading" that I mentioned earlier, or whether that's a different structure.

Unfortunately this lens has a pretty small central area where the resolution is really good, so I'd have to pan a bit to put some of the beaded-looking things "front and center", and shoot another stack. Perhaps another time -- I have other things to do today.

Doug, thanks for the kind words about these high resolution stacks versus SEM. I have a zoologist friend who assures me that there are definitely situations where the stacks give more information, for example about colors and transparency. It'll be interesting to see how the biology community incorporates this technology now that it's (relatively) cheap and easy to do.

--Rik

Ken Ramos
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Post by Ken Ramos »

Well we all now know that spiders...don't have "toe cheese." :shock: An outstanding follow up image there Rik, cool 8)

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Post by Cyclops »

Fantastic shot! I tried to get a similar shot of one of my Tarantula's foot but I couldnt get near enough DOF.
Canon 30D | Canon IXUS 265HS | Cosina 100mm f3.5 macro | EF 75-300 f4.5-5.6 USM III | EF 50 f1.8 II | Slik 88 tripod | Apex Practicioner monocular microscope

Cyclops
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some SEM images of setules

Post by Cyclops »

Rik, I did some googling and found some SEM images of these setules (I'm more familiar with the name setae, are these the smaller scale structures?)

http://images.google.co.uk/images?sourc ... &q=setules

a SEM imnage of setae:
http://www.lclark.edu/~autumn/climbing/setae.html
Canon 30D | Canon IXUS 265HS | Cosina 100mm f3.5 macro | EF 75-300 f4.5-5.6 USM III | EF 50 f1.8 II | Slik 88 tripod | Apex Practicioner monocular microscope

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Post by rjlittlefield »

Cyclops, I'm not sure about the terminology. Based on what I think the sizes are, the "setae" of the gecko are like what I'm calling "hairs" (the black things that are about 100 microns long and have the fuzzy gray spatulate tips). If that's right, then the "setules" of the jumping spider would be equivalent to the "spatulae" of the gecko. See http://www.lclark.edu/~autumn/climbing/seta.html, showing "2 million setae per gecko" and "100-1000 spatulae per seta". Perhaps this is spelled out in the full articles, which I have not tried to track down yet.

The term "setae" (singular "seta") seems to mean different things in different contexts. When I Google "define: setae", I see consistency at the level of "hair", but not much below that. I've always gotten the impression that a seta is anything that looks like a bristle but is smaller than whatever we'd call a bristle on the organism in question.

Thanks for posting a link to those SEM pictures. If you can figure out how to see them at full size, I'd be grateful. Every time I try, I just get beamed back to http://www.iop.org/ , and when I try to work my way down from there, all I can find are the text articles and small versions of the pictures.

--Rik

PS. Excellent gecko pictures, complete with scale bars, can be found here. That url is linked a couple levels down from http://www.lclark.edu/~autumn/, following "Adhesive force of a single gecko seta".

georgedingwall
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Post by georgedingwall »

Hi Rik,

Great images and a fascinating subject.

I found this link to a page about jumping spiders feet. It has a couple of SEM images on the page.

http://whyfiles.org/shorties/152sticky_spider/

Bye for now.
George Dingwall

Invergordon, Scotland

http://www.georgedingwall.co.uk/

Cyclops
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Post by Cyclops »

I see what you mean Rik, very strange!
The first few pics are all from the same site (http://www.iop.org/ )

but others are located elsewhere and i managed to find a few:

http://www.technovelgy.com/graphics/con ... etules.jpg

http://www.technovelgy.com/graphics/con ... r-glue.jpg


"At large magnifications it can be seen that single hairs (setae) are densely covered with numerous setules (image credit: Smart Mater. Struct. 13 512)":
http://nanotechweb.org/objects/news/3/4/13/Kesel.jpg
Canon 30D | Canon IXUS 265HS | Cosina 100mm f3.5 macro | EF 75-300 f4.5-5.6 USM III | EF 50 f1.8 II | Slik 88 tripod | Apex Practicioner monocular microscope

DaveW
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Post by DaveW »

I am only familiar with the term setose as used in botany. Zoology and other disciplines may use it differently. Here's what our "bible" - "Botanical Latin" by William T. Stearn says:-

Seta. bristle, bristle-like organ, as the fruit stalk of a moss.

Setaceous, Setiformis. setaceous, bristle-like.

Setifer. bristle bearing.

Setose. setose, bristly, i.e. beset with scattered ascending stiff hairs.

Setulosus. minutely setose.

DaveW

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