SPIDERS No. 49 – Attachment Discs and Drag Lines

Images made through a microscope. All subject types.

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Walter Piorkowski
Posts: 693
Joined: Mon Aug 14, 2006 6:42 pm
Location: South Beloit, Ill

SPIDERS No. 49 – Attachment Discs and Drag Lines

Post by Walter Piorkowski »






Leitz Ortholux microscope
4X Leitz projection eyepiece plus 1/3x relay lens

Image 1- Olympus 10X S Plan, 13 images at 2 micron increments.

Image 2- Leitz NPL 25x, 10 images at 1 micron increments.

Image 3- Olympus 10X S Plan, 13 images at 2 micron increments.

Image 4- Leitz NPL 25x, 9 images at 1 micron increments.

Image 5- Live subject, Both images Olympus 10X S Plan, left hand frame, image stack at 2 micron increments. Right hand frame single image.

Diffused Fiber Optic illumination
Canon 50D
Zerene PMax and Photoshop processing.

My subject for these images is a small hunting spider that doesn’t build a web to capture a meal. It is Clubiona canadensis. The subject has laid its attachment discs down against a piece of glass. Why the discs are of interest to me is that, if I am interpreting the image correctly, two separate drag lines are created, but only one is used?

These images display two different features differentiated by the thickness of the silk strand. The attachment disc silk is the thinner scribbled material that makes up the largest pattern and then two pairs of thicker strands are seen emanating from them.

In Rainer Foelix’s superb book "Biology of Spiders" a pair of images are shown that display one spinneret of the spider Drapetisca laying down a attachment disc, but with one emerging drag line. It also discusses how the single ampullate gland produces the drag line and multiple piriform glands create the attachment disc. I have tried my best to capture these glands and silk spigots in image 5 on the live subject. It has pulled the silk out of the spigot from the anchor point.

This spider for some reason places two spinnerets down at the same time, engaging both to the substrate to produce the large zig zag pattern. Both of the large red ampullate glands also lay down a pair of drag lines but only two of the four end up being used.


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