Focus stacks of a live fishing spider

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MarkSturtevant
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Focus stacks of a live fishing spider

Post by MarkSturtevant »

First, some background on this beautiful spider. The six-spotted fishing spider (Dolomedes triton) is a large-ish spider that is semi-aquatic. They are in the same family as the nursery web spiders, and their sister family are the wolf spiders. Like wolf spiders, fishing and nursery web spiders are speedy hunters and doting parents. Fishing spiders spend most of their time on water where they use floating vegetation to hunt for invertebrates and even small fish. True to their nature as water-loving spiders, they will readily dive to snag a passing minnow or to hide from danger. Those interesting behaviors I have now documented, and they will be shown later. For now I wanted to introduce these spiders in focus-stacked images that were taken in a staged setting on our dining room table.

This fishing spider was captured out on a local river while I was out with my kayak. She was not full grown, but was still large enough to encourage careful handling. I had set her out on a stage which consisted of a black plastic plate, some water (this had to be very shallow or else she would dive under it), and some lily pads. I show and explain the photography rig farther down since some features may be of interest to folks here. I would also of course welcome advice on how to better set up the equipment.

Anyway, here she is!
ImageSix-spotted fishing spider by Mark Sturtevant, on Flickr
ImageSix-spotted fishing spider by Mark Sturtevant, on Flickr
ImageSix-spotted fishing spider by Mark Sturtevant, on Flickr
ImageSix-spotted fishing spider by Mark Sturtevant, on Flickr
ImageSix-spotted fishing spider by Mark Sturtevant, on Flickr

I love these spiders! Very fast when they decide to run off, but fortunately, they just as quickly stop after going for only a short distance. I also appreciate that they don't like to jump. Even so, more than half of the stacking efforts were terminated by her suddenly deciding to clean every... one... of..... her.......8.........feet. Or by her running off. The last stack of pictures had to be cut short because of her shenanigans.

Finally, here is the rather simple rig that I had used. The Camera (5d mark iii) was mounted onto a tripod with a 'boom' arm, and the focus stacking was done with a Helicon Fb tube. The lens was the Canon 100mm f/2.8L. The light on the lens was a fluorescent ring light that was requisitioned from a dissecting microscope. Image
To the left are some supplemental LED headlights attached to 'arms' from an old Joby gorillapod tripod. I had detached one leg of this tripod and used it to extend the length of the other two legs, and to these the lights were attached. This was meant to be attached to the camera with a cold shoe mount, but the mount that I was using does not work well, unfortunately. A pity, since I would like to use these lights in the field.
Photographs were taken in "burst" mode in order to get through a stack as fast as possible. Generally, between 50-80 pictures were taken for each final picture. The pictures were combined in Zerene Stacker and touched up in Gimp.
Mark Sturtevant
Dept. of Still Waters

rjlittlefield
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Post by rjlittlefield »

Nice pictures!

I am intrigued that this spider is equally at home completely above the surface being supported by surface tension, or below the surface hunting or hiding.

Does it have any special anatomical features to let it do both those behaviors well?

Your setup looks good to me. I had to smile, remembering my own experiences with a ground spider on a floating island. Story at https://www.photomacrography.net/forum/ ... hp?t=17295 .

--Rik

MarkSturtevant
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Post by MarkSturtevant »

They are covered in a fine layer of hairs, and this traps air around their body. I expect their hairy feet helps them to stand on a layer of air when they sit or run over water. They frequently clean their feet, and perhaps they are adding an oil to their feet then.
When they submerge, I see them sort of 'dive' in rather forcefully but they generally stay right under the surface since their hairs trap a silvery layer of air around them. I have pictures of them under water to show later. They can go deeper, but they have to clamber down on vegetation to do that.

I wonder if their long 'eyelashes' do something useful for them.
Mark Sturtevant
Dept. of Still Waters

BugEZ
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Post by BugEZ »

I often see spiders at the lake shore of a local park. They venture into the water as well as scampering along the sand. We are both in pursuit of shore flies but for different purposes.

Lovely work!

Keith

MarkSturtevant
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Post by MarkSturtevant »

BugEZ wrote:I often see spiders at the lake shore of a local park. They venture into the water as well as scampering along the sand. We are both in pursuit of shore flies but for different purposes.
Lovely work!
Keith
Thanks! Some of these could be wolf spiders and nursery web spiders. Especially small ones. I expect you have these fishing spiders where you are too. I did not know about them until I specifically went looking for them.
Mark Sturtevant
Dept. of Still Waters

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