This ‘Invertebrate of the Week’ is posted in support of a crowdfunded research appeal involving these remarkable little spiders. Learn more about how you can help!
Jumping spiders (Family: Salticidae) are a remarkable group of animals and they are honestly delightful to watch whenever I have the good fortune of coming across one. I suppose ‘delightful’ is a little macabre considering the predatory nature of these animals, but they really are spectacular and usually also far from shy. It’s not uncommon to see a jumping spider moving around your garden in search of unsuspecting insects which they generally capture by using their well-developed “hydraulic” legs to propel them in a finely controlled airborne tackle before subduing their quarry with a fast acting venom that is well-suited for this type of ambush hunting.
Acrobatics aside, any amount of observation will demonstrate that theses spiders are also typically quite ‘clever’; if such a word can be appropriately applied to a spider. When hunting, some species have been known to employ circuitous attack routes or even what appear to be flanking maneuvers. They also generally appear to have the ability to remember their prey’s position even when it leaves their visual field, allowing them to negotiate complex detours to reach their target. Imagine being a jumping spider in a grassy field and trying to reach a fly you see on a distant stalk of grass. To catch it, you have to climb down the stalk of grass you are on, navigate through what is essentially a forest of grass, determine both your own position and that of the fly, sneak up on the fly once you’re close enough, position yourself, and then POUNCE! That strikes me as a rather remarkable amount of mental processing for an arachnid. Just think of how much trouble some HUMANS have finding their own car in a parking lot…and their car isn’t even on top of what is the equivalent of a tree in the middle of a forest…and they don’t have to catch it.
As you can surmise, all this complex behavior is dependent on these spiders’ sense of sight. Jumping spiders are highly visual diurnal predators and possess four pairs of eyes. Three of the four pairs are functional in all species and the remaining pair, the posterior median eyes (PME), are generally vestigial; though they have been shown to have limited motion sensitivity in some species.
Until recently, it was suggested that while jumping spiders were capable of sensing various parts of the electromagnetic spectrum (including possible UV sensitivity), they were not capable of true color vision in the way we perceive it. However, recent efforts by researchers like Lisa Taylor, Nathan Morehouse, and Daniel Zurek suggest that jumping spiders of the genus Habronattus have evolved trichromatic color vision (the same type of color vision we experience) via the addition of red sensitivity.
These small spiders reach a size of about 5-6 mm and can be found in riparian meadow environments. While the females are relatively drab, the males are highly ornamental and conspicuously colored, particularly when viewed head-on. Males of the species H. pyrrithrix for instance have bold red faces, bushy green front legs, and bright orange “knees” on their 3rd legs. When courting a female, they use these ornamental parts of their body engage in a long and highly visual courtship routine involving both visual and vibrational components.
Now, Daniel Zurek (post-doc), Sebastian Echeverri (PhD student), and Nathan Morehouse (Asst. Professor) from the University of Pittsburgh are attempting to learn more about how the recently discovered trichromatic color vision of Habronattus spiders led to the diversification of male colors in this animal group. In their own words,“The discovery of color vision in a notoriously colorful group of spiders opens up the exciting possibility of understanding how this evolutionary event may have enabled the explosive radiation of species-specific male color ornamentation. Did color vision pre-date the diversification of male color displays? How has it influenced male color since?”
Though this sort of foundational research is critical to our appreciation of the natural world (and to potentially aiding in the development of new methods and technologies), it is heavily underfunded…but you can help! Daniel and the team are currently seeking a relatively modest sum of money in the amount of $6000 to finance their research. Please check out their appeal below and learn more about how you can help break new ground in jumping spider research by visiting their crowdfunding page on Experiment.com.
References and Further Reading:
- Taylor, L. A., D. Clark, and K. J. McGraw. 2014. Natural variation in condition-dependent display coloration does not predict male courtship success in a jumping spider. Animal Behaviour 93: 267-278. PDF.
- Taylor, L.A., E. B. Maier, K.J. Byrne, Z. Amin, and N.I. Morehouse. 2014. Colour use by tiny predators: jumping spiders exhibit colour biases during foraging. Animal Behaviour 90: 149-157. PDF.
- DB Zurek, AJ Taylor, CS Evans and XJ Nelson (2010). The role of the anterior lateral eyes in the vision-based behaviour of jumping spiders. Journal of Experimental Biology 213(14) 2372-2378. PDF