Monday, August 14, 2017

Cute Jumping Spider

"They went that-away"  -  REK
Walking the gravel bar looking for fossils I saw something tiny jump among the rocks.  It was this bold little jumping spider searching for food.  Each jump is quick and it always landed on top of a small rock, a good perch to look around from.  After I took a number of photographs I got down to ground level to get a face picture and it tried to distract me by pointing in another direction - very clever spider!

Wolf Spiders (1) and Jumping Spiders (2)
It is important to get a full frontal face shot when possible to see the eye pattern.  The number of eyes and their arrangement can be compared with commonly available eye diagrams.  Unlike most other spider families, the Salticidae have flat faces with large eyes pointing straight ahead.  Large eyes can be an adaptation to gather light for night vision, but in this case they specialized for prey identification and measuring the range to land directly on their prey.  This explains its landing on top of a rock every time!

Like most spider families they actually have four pairs of eyes but the other two sets are on top of the head.  They provide lateral vision looking for movement rather than focusing on the object.  I tested this by moving my hand to its side.  Sometimes this made it jump but with a slight movement it would make a tiny hop, turning 90 degrees to face me.



Identifying spiders to species is challenging but this is the rare exception.  Even in the deep shade its metallic green color was impressive.  This is a male Emerald Jumping Spider, Paraphidippus aurantius, as confirmed on Bugguide.

"Look deep into my eyes, you slow human." - REK
Jumping spiders, Salticidae, are the largest family of spiders with more than 500 genera alone.  They are the rock stars of the arachnid world with lots of Youtube videos titles adding "cute."  So far none have created a music video but they just might crowd out the cat video craze with time.  Arachne.org from Australia describes "The courtship of some genera including Maratus the Peacock Spiders feature a complicated ritual of leg waving, toe-tapping, abdomen twerking, and wing flapping."

Part of their cuteness comes from the way they look up and watch you, especially those that people keep as pets.  Yes arachnophobes, some people actually keep them. 

 Tree of Life provides further details:
"Jumping spiders are charming spiders that look up and watch you. Their excellent vision allows them to hunt much as do cats, spotting prey from long distances, creeping up then pouncing using their jumping ability. Although a jumping spider can jump more than thirty times its body length, none of its legs has enlarged muscles. The power for jumping probably comes from a quick contraction of muscles in the front part of the body increasing the blood pressure, which causes the legs to extend rapidly much as in the toy frogs that hop when you squeeze a bulb."
Thus far I have not considered testing the strength of our marriage vows by bringing a "cute" jumping spider home.  More on that in a later blog?

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