Color plays a significant role in the courtship rituals of some jumping spiders, like Habronattus pyrrithrix. Male jumping spiders can be covered in patterns that include bright reds and oranges. Despite this, scientists have only identified photoreceptors for green and ultraviolet (UV) light in the eyes of H. pyrrithrix. In a study published in Current Biology this week (May 18), researchers at the University of Pittsburgh reported on their discovery of a light-filtering strategy H. pyrrithrix uses to broaden its color perception.
“It’s a sweet way of solving the problem,” Gil Menda, a neuroethologist at Cornell University in Ithaca, New York, who was not involved in the study, told National Geographic.
The Pittsburgh team sectioned H. pyrrithrix retinas and shined light through them to determine which colors the arachnid can detect. In addition to the green and UV photoreceptors, the team found a red pigment in the center of two of the animals’ retinas. They determined that the pigment serves as a long-pass filter that only lets red light pass through to underlying photoreceptors. This strategy essentially provides the spiders with a third color channel that can discern reds and oranges. The researchers also found the filtering pigment in four other species of jumping spiders.
Because H. pyrrithrix can perceive UV and green wavelengths in addition to the reds and oranges, study coauthor Nathan Morehouse, an evolutionary biologist at the University of Pittsburgh told National Geographic that “in principle, they can see an even broader spectrum of colors than we can.”