What Jumping Spiders Teach Us About Color

Color Vision in Jumping Spiders

• Jumping spiders have unique eye structures that allow them to see fine detail and color in a narrow slice of the world.
• Different species of jumping spiders have different types of color vision, with some being dichromats, some being trichromats, and some being tetrachromats.
• The ability to see red has evolved several times in jumping spiders, suggesting that color vision is an important trait for their survival.
• Jumping spiders have expanded color vision compared to other arachnids, with some species being able to see up to 12 colors.

Methods to Study Color Vision in Jumping Spiders

• Scientists collect jumping spiders from various locations to study their color vision and identify the species with expanded color vision.
• Microspectrophotometry is used to measure the wavelengths of light absorbed by individual cone cells in the spider's retina, determining their color vision capabilities.
• Behavioral experiments are conducted to confirm the spiders' ability to see specific colors by showing them moving shapes on a screen and observing their responses.
• Transcriptome sequencing and immunohistochemistry are used to identify the genes responsible for expanded color vision and their expression in the spider's eyes.

Evolution of Color Vision in Jumping Spiders

• Jumping spiders have evolved new forms of color vision multiple times independently, with different species acquiring their new visual capabilities in various ways.
• Some jumping spiders gained the ability to see red through gene duplication and evolution of the green-sensitive opsin gene, while others developed internal filters to selectively respond to longer wavelengths.
• Jumping spiders have evolved expanded color vision by using a filter in front of some of their green-sensitive cone cells, allowing them to see red.

Ecological and Behavioral Implications of Color Vision

• Researchers are investigating the evolutionary advantages of expanded color vision in jumping spiders, particularly in distinguishing between palatable and unpalatable prey.
• Experiments with Habronattus pyrrithrix, a jumping spider with good color vision, showed that they can learn to avoid red-painted, bitter-tasting termites and prefer gray-painted, tasty termites.
• Spiders with access to color cues performed better, laying eggs sooner and weighing more at the end of the experiment, suggesting a fitness advantage.
• Surprisingly, some male jumping spiders display bright red colors during courtship, even though female jumping spiders lack the ability to see red.
• Red coloration in male jumping spiders might create a depth illusion, making them appear closer to females and potentially influencing their courtship behavior.
• Red coloration in prey items could also be a strategy to deceive jumping spiders, making them appear closer and increasing their chances of escape.

Eye Movements and Color Perception

• Jumping spiders have unique eye movements that affect their perception of depth, color, and focus.
• High-resolution X-ray videos of live spiders' eyes are being collected using the Advanced Photon Source to study these eye movements.
• The spiders' retinas can move horizontally, vertically, and twist to change their field of view.
• The researchers are investigating how these eye movements impact the spiders' ability to focus, sense depth, and perceive color.
• Color vision in jumping spiders may be three-dimensional in a way that is different from human color perception.

Conclusion

• The study of jumping spiders' color vision provides insights into the evolution of color vision and the diverse ways it can manifest within a single group of animals.
• Color is not an intrinsic property of an object or solely a mental construct but emerges through the co-evolution of eyes and the world they perceive.