New images show microscopic structures that manipulate light to create the dark patches

peacock spider

BLACK OUT  Microscopic lumps on man Maratus speciosus peacock lions (revealed ) make some of their black spots appear darker, which may help the arachnids bring a mate.

Male peacock spiders understand how to put on a show for prospective mates, with dancing and a bit of optical trickery.

Microscopic lumps on the arachnids’ exoskeletons make velvety black areas seem darker than a typical black by manipulating light. This architecture reveals less than 0.5 percent of light, researchers report May 15 at the Proceedings of the Royal Society B.

The ultradark stains, found near vibrant colours on the lions’ abdomens, make an”optical illusion which the colors are so bright… they’re practically glowing,” says Harvard University evolutionary biologist Dakota McCoy.

Male peacock spiders swing and shake their brilliantly colored abdomens during complicated mating displays. Pigments produce the red and yellow hues, but blues and purples are derived from light interacting with hairlike scales (SN: 09/17/16, p. 32).

Black regions on the lions contain pigment, too. But studying electron microscopy also revealed a landscape of little lumps in superblack spots on Maratus speciosus and M. karrie peacock spiders. In contrast, all-black, closely related Cylistella spiders possess a smooth feel.

Bumps galore

Scanning electron microscope images reveal lumps, which manipulate incoming lighting, in superblack spots over the abdomens of 2 species of peacock spiders. Even though Maratus speciosus (abandoned ) has only lumps, M. karrie (middle) also sports spiky scales which restrict manifestation by scattering and absorbing light. A Cylistella spider (right) has a smoother surface, which ends in an ordinary black look.

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