Skip to content

SciTech

Green light for jumping spiders

by Dave Armstrong 28 Jan 2012
Green light for jumping spiders

This cute H. adonsoni jumping spider shows four of his eight eyes via Shutterstock

The zebra spiders and their allies (the Salticidae group) are jumping spiders that catch their prey without a web. In order to jump accurately on flies or other prey and fine-tune their capture technique, their 3D vision has to be perfect. Unlike the binocular approach of humans (stereopsis) or the insect method which moves the head from side to side to achieve a parallax by means of motion, these spiders use an image defocusing system to judge the relative distances involved.

Hasarius adansoni has eight eyes, with the outer two used for movement detection. Two central, "primary" eyes have four layers of photoreceptors. Two layers detect green light, one receiving focused images and the other receiving fuzzy (out-of-focus) images; with the two layers closest to the surface sensitive to ultraviolet light.

Osaka and other universities have been investigating the opsins(colour chemicals) of Arthropods and the colour vision of spiders for many years. This Japanese research showed that green light was necessary for accuracy since the spiders were able to judge their jumps successfully in green light. Presumably, they used the two layers closest to the retinal surface. In red light (which does not contain the shorter wavelength green light) many spiders could not jump accurately. The researchers then created a mathematical model to predict how inaccurate the jumps would be under different wavelengths of light. The model did predict the spiders' performance exactly as foreseen. These animals are therefore unique in using this depth perception technique.

Dr. Takashi Nagata of Osaka City University and several of his colleagues have published this research in the current Science journal. Japanese scientists and others have been investigating spider vision because of its unique mechanisms. The suitability of this system for robotic vision in the future seems high.

Jumping spiders shown under green and red light; Credit: © Science/AAAS

Computers or simple robots could more easily observe motion if they were able to simply focus on objects and, at the same time, detect the unfocussed image for this motion parallax to be achieved. Rapid detection of motion in an area or in a specific object could be used in surveillance, or as a vision system in new types of camera.


Trending Eco-Friendly Clothing

Love My Planet Women's Relaxed Fit Hoodie
Earth
Quick Add
Close
Notify me
Notify me
Love My Planet Women's Relaxed Fit Hoodie
Love My Planet women's eco-friendly relaxed fit hoodieSize Guide Centimeters 8 10 12 14 16 18 Bust 84 88 92 97 103 108 Waist 66 70 75 80 85 91 Hips 91 95 99 104 109 116 Bust: Measure around the fullest part of...
£38.00
£38.00
Close
Notify me
Notify me
Penguins Hate Push-Ups Men's Pullover Hoodie
Earth
Quick Add
Close
Notify me
Notify me
Penguins Hate Push-Ups Men's Pullover Hoodie
Penguins Hate Push-Ups men's eco-friendly pullover HoodieSize Guide Centimeters XS S M L XL XXL Height 171 175 179 183 189 195 Chest 86 93 99 104 116 129 Waist 71 76 81 89 99 112 Chest: Measure all round your chest just below...
£38.00
£38.00
Close
Notify me
Notify me
Lightning Bolt Kids Long Sleeve T-Shirt
Earth
Quick Add
Close
Notify me
Notify me
Notify me
Lightning Bolt Kids Long Sleeve T-Shirt
Lightning Bolt kids eco-friendly long sleeve t-shirtSize Guide Centimeters 3-4yrs 5-6yrs 7-8yrs 9-10yrs 11-12yrs Height 98 112 125 136 147 Chest 60 66 70 75 84 Chest: Measure all around your chest just below your armpits. Height: Your natural height If you fall between...
£18.00
£18.00
Close