
If you have ever approached a tiny spider that jumped suddenly far and fast you’ve probably seen a jumping spider (Salticidae), one of 6000 species on Earth.
Jumping spiders are harmless to humans and can be identified by the position of their eyes. They have four pairs(!) with the largest front and center. As for jumping, they use their back legs.
Jumping spiders’ well-developed internal hydraulic system extends their limbs by altering the pressure of their body fluid (hemolymph) within them. This enables the spiders to jump without having large muscular legs like a grasshopper. Most jumping spiders can jump several times the length of their bodies.
— Wikipedia: Jumping Spider
When not jumping I’ve seen them move in a jerky fashion.
Phidippus mystaceus jumping spider momentarily distracted by a passing velvet mite.#salticidae #trombidiidae #arachnida pic.twitter.com/8BQjgQls7E
— Thomas Shahan (@ThomasShahan) January 17, 2021
Like a furry robot.
(photo from Wikimedia Commons; click on the caption to see the original)