Image 1
Spinnerets and cribellum of the crebulate spider genus Ubolorus. View with spider on its back.
Nikon 10X Achromat
Diffused fiber optic illumination.
101 images at 5 micron increments.
Image 2
Close-up of four spinnerets, plus at the top of the view, the cribellum. An additional silk producing organ of the crebulate spiders. It is more of a flat plate than a cone shaped projection, like the spinnerets.
Nikon 20X Achromat
Diffused fiber optic illumination.
165 images at 2 micron increments.
Leitz Ortholux microscope
4X Leitz projection eyepiece plus 1/3x relay lens
Canon 50D
Zerene PMax stacking.
Processing in Photoshop, Bibble Pro5
It is almost too amazing to believe, but there are spiders that have a silk producing organ of extraordinary complexity that is not a spinneret. The organ is called a cribellum and is flat or plate like and resides below the more external spinnerets. This remarkable organ contains tens of thousands of minute silk spigots. In some spiders, over 40,000!
The spigots are as expected are extraordinarily small and produce silk strands only 0.01 micrometers in diameter. The huge number of micro fine strands are woven together to create a type of silk that looks like wool under the microscope and snags the fine hair projections of any insect touching it. No need for stickiness.
These micro fine strands are manipulated by the back legs of the crebulate spider by a comb like feature called the calamistrum, which is the subject of part two of this installment.
Unfortunately, spigots and silk strands of this size are beyond the resolution of my optical microscope so image number two is unable to show any details on the cribellum.
Walt