Jumping Spider – Colonus sylvanus

Jumping Spider – Colonus sylvanus

color photo Jumping Spider Colonus sylvanus

This is a large male jumping spider at 10mm

He was out hunting for prey and females in the leaf-litter on the forest floor at Castle Rock State Park in Illinois, along the banks of the Rock River. I was only able to follow him for a short while – as soon as they notice you watching, they almost always become surreptitious in their movements.

The jumping spiders forage for their prey in the daytime. They approach prey slowly and, when a short distance away, make a sudden leap onto the unfortunate animal. They are good jumpers and can leap at least 10 times their own body length.

I saw one jump off a tree stump to snatch an insect in mid-air and instantly swing back to the stump Tarzan-style via their lifeline, then hoist itself back to the starting position in a matter of seconds. I was surprised seeing it done the first time. I always thought they just dragged that single thread around so if they fell they could get back up – I wonder why I had never imagined they had an even better purpose for it?

color photo frontal view Jumping Spider Colonus sylvanus

Jumping spider’s anatomical points of interest:

  • Esophagus passes straight through the brain
  • Portion of gut overlies the eyes and brain inside carapace
  • Heart extends from abdomen into cephalothorax
  • Leg muscles attached inside the carapace operate legs like marionette puppets
  • Jumping spider’s brain volume to body size proportionate to human, but visual processing region is larger
  • Salticids move retinas inside the eyes to look in different directions, as the lenses are fixed in the carapace

color photo Colonus jumping spider lateral view

It’s a different world down here in the weeds. The colors and structures are amazing – it’s the greatest show on earth! All free, you just gotta look.

color photo colonus jumping spider dorso-lateral view

This is one wild spider. I love the jumpers. I wonder if you think I’m nuts?

Reference: Bugguide.net Colonus sylvanus

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