Spectral filtering enables trichromatic vision in colorful jumping spiders

Summary Jumping spiders (family Salticidae) are masters of miniature vision, achieving higher spatial resolution in relation to body size than any other animal [1]. While most members of this family do not use color in intraspecific communication, several genera serve as emerging examples of rapid evolutionary radiation in sexual display coloration [2]. These include the Australasian Maratus ‘peacock' spiders, and the American genus Habronattus . Males of these genera are often brilliantly colored on body surfaces they showcase to females during elaborate courtship dances (Figure 1A). However, molecular and electrophysiological data suggest that color vision in the acute ‘principal' eyes of most jumping spiders is based on only two types of photosensitive pigment, one sensitive to ultraviolet (UV) light, the other to green light [3–5]. We report here that Habronattus jumping spiders may achieve substantially better color vision via a mechanism previously unknown in spiders: the shifting of sensitivity of a subset of their photoreceptors from green to red via a long-pass filter positioned in their retina. Trichromatic vision resulting from this filter system should markedly enrich these animals' perception of color, including reds, oranges and yellows often found in their courtship displays.