Unlike Most Other Arachnids, Majestic Jumping Spiders Can See In Color

With the flick of a leg and shuffle of a foot, the jumping spiders really know how to dance a jig. And just like the best ballroom dancers, they pair their rhythmic movements with the sparkle and dazzle of bold and flashy colors. Yet the majority of spiders don’t actually see in color, which begs the question: Why are some jumping spiders so damn jazzy?

“It's rare to see bright colors on most spiders, as they don't usually have the visual sensitivity to perceive color beyond drab blues, greens and browns,” explains Nate Morehouse, who has presented his study at the 2017 Annual Society for Integrative and Comparative Biology Conference in New Orleans, in a statement. “But certain groups of jumping spiders deviate from this pattern.”

Jumping spiders, or to give them their scientific name, Salticidae, are the largest group of arachnids, comprising some 5,800 species. But out of all of these, it turns out that only two groups possess the rare ability to see in color. In addition to the blues, greens, and browns, these eight-legged anomalies can also see reds, yellows, and oranges.

^{Peacock spiders are pretty showy. Jurgen Otto}

The researchers think that this could help explain why the males of these groups display dazzling colors, which are splashed across their faces and bodies. They think that in addition to the males' fancy footwork to woo lady spiders, the bright colors are used in conjunction to add a bit of razzmatazz.

^{The spiders are very tiny, but very beautiful. Jurgen Otto}

But even more curiously, the two groups that have evolved the ability to see in color are not actually that closely related, and have even settled on different ways to view the world in technicolor. While those belonging to the Habronattus genus of North and Central America have developed, in effect, a red filter to go over their retina, the Maratus genus found in Australia has managed to evolve an entirely new type of red sensitive retinal cell. Two different solutions to get the same result.

^{Not just colorful, they're also fancy footed. Thomas Shahan}

“This is a remarkable discovery, as two different groups of jumping spiders have evolved on opposite ends of the globe,” says Morehouse. In fact, the Habronattus genus is as far from the Maratus genus as humans are to hyenas. “Both have the rare ability to see long wavelength colors like red, orange and yellow. But each group has arrived at independent solutions for seeing the color.”

The next step is to broaden Morehouse’s study and investigate other brightly colored arachnids, such as those in India that are completely unrelated to both jumping spider groups looked at so far.

 

^{Not just flashy, some of the spiders are pretty floofy, too. Jurgen Otto}