Spider silk

Spider silk; just a few fundamentals.

Nature endowed most spiders (Arachnids) with a complex array of glands to produce several different silk  fibers. Some spiders have up to 7 glands to meet their lifecycle needs. There are generally fibers for trapping food, for making a trapeze on which to spin radial strands, spiral strands, sticky spiral lines, and cocoons. The trapeze, or frame

Silk from a spider web stretched between a 4 half-gallon milk cart plastic container and a trash container. Top fiber, from the web frame is probably 2.5-4 um. Bottom fiber is probably a spiral  line with beads of glue on it or two lines.
Spider web with two 3-mm to 4-mm cocoons attached to a 4-milk half-gallon shipping container and trash container(not pictured). In the upper center to the right of the smaller cocoon the reflective shimmer is a frame line of the web stuck to the container. Shimmer about the cocoons are web radial and spiral fibers. Sorry the image and light could be better.
A spider web taken in 2010 after rain in Hawaii. The upper frame fiber is about 20 centimeters from the right hand end attached to the bush to the attachment on the left not in the picture. The  web, about the size of your palm,  is a mosaic of  droplets.   Sticky spiral segments stand out.  Radial segments spun from a different gland set do not hold the droplets as well and do not show up as clearly.

lines attach to  fixed points with a sticky cement. The material properties of fibers varies however gram for gram spider silk is about the toughest material. The combination of strength and ductility gives dragline silks a very high toughness (or work to fracture), which “equals that of man-made polyaramid (aromatic nylon) filaments, which themselves are benchmarks of modern polymer fibre technology” (Vollrath, F. & Knight, D. P. (2001). “Liquid crystalline spinning of spider silk”. Nature. 410 (6828): 541–548. Bibcode:2001Natur.410..541V)

I’m learning about spider silk and if you have questions just sock the bits to me…

to be continued

Note… so what are microns (micrometers) anyway? You are 183-centimeters tall, stack 183 cubes to your height. One cube is one centimeter. Stack 10 cubes  into that centimeter, each is one millimeter, then stack 1000 cubes into that millimeter cube.  The stack of 183 cubes is now a stack of 183-cmX10-mm/cmx1000-um/mm, or 1,830,000-um cubes high. Remove 2.5 cubes. They are about the thickness of spider silk. What is the resolution of the human eye? A very complicated story. A germaine  answer to the problem is in normal light, at a normal distance, with a normal eye, reflecting in the highest wavelength off two closely spaced dots, resolution reading is according to wikipedia “Observing a nearby small object without a magnifying glass or a microscope, the size of the object depends on the viewing distance. Under normal lighting conditions (light source ~ 1000 lumens at height 600–700 mm, viewing angle ~ 35 degrees) the angular size recognized by naked eye will be round 1 arc minute = 1/60 degrees = 0.0003 radians (Yanoff, Myron; Duker, Jay S. (2009). Ophthalmology 3rd Edition. MOSBY Elsevier. p. 54. ISBN 0444511415). At a viewing distance of 16″ = ~ 400 mm, which is considered a normal reading distance in the USA, the smallest object resolution will be ~ 0.116 mm. For inspection purposes laboratories use a viewing distance of 200–250 mm,[citation needed] which gives the smallest size of the object recognizable to the naked eye of ~0.058- 0.072 mm(~55-75 micrometers). The accuracy of a measurement ranges from 0.1 to 0.3 mm and depends on the experience of the observer. The latter figure is the usual positional accuracy of faint details in maps and technical plans”.

Boiling it down, you can resolve a human hair at 100-um to 300-um. So, why do you “see” spider webs? You don’t. You see light “shimmering off like a prismatic effect”. And thank you foldscope for enlarging resolution by 140 times so we can examine tiny stuff.

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