Iridescent Spider Video

[BillT]

Great video of a fast moving iridescent jumping spider.
Also has some mating behavior (I think).

Iridescence is different from "normal" colors in things (including animals). Normally a chemical will absorb or reflect different specific wavelengths of light (electromagnetic radiation). These chemicals (also called pigments) can be extracted and isolated in a test tube, combined with other pigments and applied to other objects.

Another class of color generators produce iridescent colors. These are structural colors. They do not depend upon a specific chemical composition.
Instead they present incoming light with different reflecting surfaces. Some of the incoming light reflects from each surface, each surface then is a source of the wavelengths at different distances (at a very small scale). If the reflecting surfaces are spaced at regular intervals and are a multiple of the wavelength of one of the incoming light. The light from these different sources combines (constructively or destructively) at the viewer's location to generate specific wavelengths of light due to the interference patterns of the reflected light.

Fish do this by making guanine crystals in their idirophores (reflecting pigment cells) and making them parallel to the fish's surface.
The spider (and butterflies) have little tiny scales on certain parts. You can wipe them off with your finger sometimes. The scales have little fibers coming off them (picture in article below).

Link to article describing the iridescent scales:
http://rsif.royalsocietypublishing.org/content/13/121/20160437
(epi-illumination is illumination from the side you are looking at it from; trans-illumination is illumination from behind)

[Ron Sower]

Great read! Thanks, Bill!

[Mugwump]

...now that's different.....good article