Spiders No.1 – Weapons of an Orb Web Weaver

[Walter Piorkowski]

Leitz Ortholux microscope.
4X Leitz projection eyepiece plus 32:1 relay lens.
Leitz 4X Plan fluorite objective.
Horizontal F.O.V. 2.5 mm.
Image stack, 86 images at .001 increments.
Reflected light, diffused fiber optic illumination.
Canon 50D
Zerene and Photoshop processing.
Live subject.


I have been observing our spider friends this summer. I have been getting excellent results from Zerene Stacker, so I have a series of images to share.

This orb web weaver once finished with its web likes to sit crouched with its legs close to the body to reduce its profile. The four front legs are set out well in front of the chelicera. Although the strike of this web builder is too fast for my eyes to see, the spiked front legs of this species are certainly likely to impale and hold the hapless victim.

Walt

[Franz Neidl]

These are great pictures! Congratulations.
But I have also a question: You write "Live subject". How is it possible to make a stack with 86 pictures? Is this animal so quiet? (I dont understand almost nothing about spiders).

Franz

[Walter Piorkowski]

Hello Franz and thank you. There are many kinds of spiders and many niches that they occupy in nature. Some are constantly on the move hunting for food. Others like my subject here will build an elaborate silk web in which they will centrally locate themselves. They will sit motionless for sometime as they wait for a disturbance in the web. At this time they move with blinding speed to kill what has disturbed their web.
I have found that mature spiders of this type will sit for 5-10 minutes or so. I have to work fast and have many failures, but live subjects are more interesting to me. Their mouth parts seem to be in motion more frequently but this can usually not be seen except from their underside.

Walt

[rjlittlefield]

Franz, I can confirm that these orb-weavers are often agreeably still. See for example the setup HERE and the image HERE of a spider that is closely related to Walter's.

In contrast, some other spiders seem always in motion and can be photographed live only when knocked out by some anesthetic like CO2. Those are much harder to deal with (though even the agreeable ones are hard enough!).

--Rik

[Charles Krebs]

Walter,

Excellent set of shots!

What do you figure the magnification (on sensor) is with either the 4x or 10x objectives as you are set up?

[Walter Piorkowski]

Hi Charles. You will have to give me some time to calculate the magnification. It is not as easy as measuring off of film. I have done it in the past and should do it soon for the setup I used on these images. I have to find my old notes.

Walt

[Walter Piorkowski]

Hi Charles. I have the answer to your at sensor magnification question. The magnification for the 4x objective images are 6x and the 10x objective, 16x.

Walt

[Cactusdave]

I just got a reasonably priced Leitz X4 Plan Fl on Ebay. I don't have a real low power on my Ortholux setup and it looks a good lens judging by your outstanding results. I don't have that very useful magnification reducing camera coupling lens you have however, so I doubt I'll be trying it on any spiders!

[Walter Piorkowski]

Hi Dave. I think you will be quite happy with that 4x Leitz, it is an excellent objective. Regarding the reflex and relay lens setup, they are on Ebay also every once in a while. If you go for one make sure it is a 1/3x or 0.32 and not the 1/2x.
Walt