The colors are produced not by pigments but by tiny scales with microscopic curves and gratings that refract and diffract light to separate and reflect various wavelengths. This works somewhat in the same way that a film of oil on a surface produces an array of iridescent hues.
Studying the color-producing structures in these arachnids has given scientists ideas for new color technologies.
Here's a video of the mating displays of several species of these spiders set to music. It's astonishing to consider that these spiders are less than 5 millimeters in size and that the information that directs their displays plus all the other behaviors in which the spider engages as well as the production of the vari-colored abdomens is all packed into a brain that's the size of a pinhead:
Here are a few more interesting questions and points raised in the article:
The artistic patterns on the males’ abdomens seem gratuitously beyond anything necessary for mating. Drab animals get by just fine; why the excessive color and beauty? And why the dozens of variations among different species? We could be forgiven for imagining a designing intelligence with an artist’s eye.We might all wonder this as well. Especially might we wonder "how the spiders assemble these fancy structural patterns in the first place" if we limit ourselves to thinking that this amazing creature must have evolved these gaudy patterns and complex behaviors through an unguided, random process like Darwinism.
Aesthetic considerations, furthermore, lead us to ask why human beings are the only ones who get excited about the mating dances of an unrelated species. Does that speak to human exceptionalism? We don’t see any other animals, except the female spider, watching the performances, but people by the millions are fascinated by these tiny animals that have nothing to do with their own “fitness.”
What is the evolutionary explanation for the quality of charm? Of humor? Or enchantment? We don’t eat them or train them to do our work. How did our curiosity, sense of humor, and love for beauty “evolve”?
“Who knew that such a small critter would create such an intense iridescence using extremely sophisticated mechanisms that will inspire optical engineers,” said Dimitri Deheyn, Hsuing’s advisor at Scripps Oceanography and a coauthor of the study.
“As an engineer, what I found fascinating about these spider structural colors is how these long evolved complex structures can still outperform human engineering,” said Radwanul Hasan Siddique, a postdoctoral scholar at Caltech and study coauthor. “Even with high-end fabrication techniques, we could not replicate the exact structures. I wonder how the spiders assemble these fancy structural patterns in the first place!”