SERIES: Invertebrate of the Week

Invertebrate of the Week #13 – Habronattus Jumping Spiders

Habronattus pyrrithrix courtship display
Habronattus pyrrithrix courtship display. Photo: Danel Zurek (http://goo.gl/ZzCZt1)

Jumping spiders (Salticidae) are a remarkable group of animals. They are also delightful to watch whenever you have the good fortune of encountering one. I guess ‘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 common to find them moving around your garden in search of insects. They use their great eyesight and well-developed “hydraulic” legs to propel them in a finely controlled airborne tackle before subduing their quarry with a fast-acting venom.

Acrobatics aside, any amount of observation will demonstrate that these spiders are also typically quite clever. When hunting, some species employ circuitous attack routes and flanking maneuvers to gain the upper hand in a hunt. Remarkably, they also 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 you’re a jumping spider in a grassy field and you’re trying to reach a fly 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 attack. That’s a remarkable amount of mental processing for an arachnid.

Illustration of jumping spider vision
Illustration of jumping spider vision by David Hill (http://goo.gl/JdQdxq)
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All that complex behavior is dependent on these spiders’ sense of sight. Jumping spiders are highly visual diurnal predators with four pairs of eyes. Three of those 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.

I was previously thought 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. Recent efforts by researchers like Lisa Taylor, Nathan Morehouse, and Daniel Zurek, however, 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.

Habronattus pyrrithrix female and male. Photo: Danel Zurek (http://goo.gl/ZzCZt1)
Habronattus pyrrithrix female and male. Photo: Danel Zurek (http://goo.gl/ZzCZt1)
Habronattus pyrrithrix jumping spider color vision. Photo: Danel Zurek (http://goo.gl/ZzCZt1)
Habronattus pyrrithrix color vision. Photo: Danel Zurek (http://goo.gl/ZzCZt1)
Left to right: H. coecatus, H mustaciata, H. hallani, H. calcaratus. (Images: Colin Hutton - http://www.colinhuttonphotography.com/spiders)
Left to right: H. coecatus, H mustaciata, H. hallani, H. calcaratus. (Images: Colin Hutton – http://www.colinhuttonphotography.com/spiders)
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Habronattus jumping spiders are small, reaching a size of about 5-6 mm, and are 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 those ornaments to engage in a long and highly visual courtship routines involving both visual and vibrational components.

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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 modest sum of money in the amount of $6,000 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.

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!

References and Further Reading:

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