Bumps on the peacock spider make dark spots super-dark

A team of researchers consisting of members of Harvard University, the University of Bonn, the University of Denmark and Yale University identified bumps on the ground. abdomen of male peacock spiders that make their dark-colored patches even darker. In their article published in Acts of the Royal Society B, the group describes his study of moguls and what he learned about them.

The Maratus or Peacock spider, native to Australia, is tiny (only 4 to 5 mm long) and is known for the bright coloring of the male abdomen. Males use the colorful display as part of a dance that they perform to woo women. The colorful abdomen has attracted the attention of researchers because of its intensity. Some descriptions say that it seems to shine. Previous research had shown that yellow and red tints were due to pigmentation, while purples and blues were due to scales resembling hair. To better understand how the little spider could create such a vibrant display, the researchers observed several specimens under the electron microscope.

The researchers explained that the colors were so striking on the abdomen because the black and velvety parts next to them were incredibly black. When they looked closely at the black parts, they observed bumps with a unique structure. When they reproduced the reliefs in a simulation, they discovered that they manipulated the light in two ways to reduce the reflection. First, their curved surfaces bounced the light in random directions, directly reducing the reflection. And second, they discovered that each of the bumps was a tiny microlens – each forced light entered a longer path when it interacted and was eventually absorbed by the black melanin pigment. Together, the features of the reliefs reflected less than 0.5% of the light that struck them.

Researchers note that spiders are not the only creatures that manipulate light to create exceptionally striking colors – previous research has shown that the rich colors displayed by birds of paradise, for example, are also due to tiny structures, this time in their feathers, making the black parts darker.

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