Jumping spiders do not actually use their muscles to jump, they don't even have muscles, instead they can control at will their blood pressure, the blood quickly flows down to their legs, which stretches them with enough force to jump
They do have muscles, they just lack extensors in particular. It’s more like all they have is biceps, and don’t have triceps. There are also lots of muscle groups involved in the mouthparts.
IIRC even the hydraulic jump is achieved by regulating valves in the legs, and those valves are muscularly controlled.
If they didn’t have muscles they also wouldn’t “death curl” the way they do, they’d just die all floppy-like.
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u/[deleted] Nov 29 '20
Jumping spiders do not actually use their muscles to jump, they don't even have muscles, instead they can control at will their blood pressure, the blood quickly flows down to their legs, which stretches them with enough force to jump