Research

The spots of peacocks of spiders practically do not reflect light. Why?

The males of peacock spiders know how to attract females: using dance and optical tricks. What kind? Microscopic bumps on the external skeletons of these arachnids make velvety black areas darker than normal black, manipulating light. Such an architecture reflects less than 0.5% of the light, scientists reported in a paper published May 15 in Proceedings of the Royal Society B.

What is the secret of dancing spider?

"The super dark spots that can be found next towith motley and bright colors on the abdomen of the spider, they create an optical illusion that the colors are so bright that they almost glow, ”says evolutionary biologist at Harvard University Dakota McCoy.

The males of spiders sway and shake theirpainted abdomen during the difficult marriage ceremonies. Pigments create red and yellow shades, but blue and purple colors are due to light interactions with hair scales.

Black areas on spiders also contain pigment. But scanning electron microscopy also revealed the landscape of tiny bumps on the Maratus speciosus and M. karrie spiders. On the contrary, completely black, closely related spiders Cylistella have a smooth texture.

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Using modeling, McCoy and her colleaguesshowed that because of the bumps dark spots look even darker. Curved surfaces reflect light around and scatter it in such a way that it leaves the field of view of the looking female. And the bulges act as microlenses, bending the incoming light in such a way that it goes a longer way and spends more time interacting with the light absorbing black melanin pigment than it would have spent if the surface were flat.

The luxurious appearance of the spiders reminds of heavenlybirds that also use tiny structures to create ultra black feathers. But those and other animals developed their abilities separately. And this phenomenon may not be so rare. According to McCoy, snakes, beetles, and other birds have super-black shades.

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