Physics of Jumping spider

Question

I recently viewed this video:

httpss://www.youtube.com/watch?v=FhpL5h8sEHo  (without the s after https)

i really dont understand how the high blood pressure acts on the legs. The physics i understand is that - A body to do some action needs to put opposite force on the stationary body for relative motion, yearning a reaction force on the body itself thus providing motion. But you can see that the spiders legs are frail, weak, then a sudden high release of blood would destroy the legs. And even for that high blood preassure, the legs must have enough strength to bear the high pressure, which it doesnt look like it can. 

I know impulse provides large forces in short time to provide more energy, but does it concern an area of action? I suppose the impulse acts on a point of their legs to generate more pressure to lift, but it doesnt even look like its been concentrated at a point while it propels. It seems like the power to jump is coming from somewhere else.

Can someone please explain me the science behind its jumping? It would be really grateful for the community and me, as this jumping nature keeps bugging me.

Comments

Nice video. Should 'relativistic action' read 'relative motion'? (''relativistic'' suggests motion close to the speed of light, which it isn't...)

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Yes, my bad, its relative motion.@ArnoldNeumaier But this wont work in scaled up model right? like in bigger bots?

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I corrected the language. 

Whatever the detailed mechanism, these things never scale. Small objects move far more easily than large ones. A flea jumps far wider than 4 times its length (as the spider in the video does).