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I understand that one does not simply scale up the smallest of creatures to the size of megafauna without violating basic physiological constraints like the square/cube law, among others; so what would have to take place to take a grasshopper and enlarge it to the relative size of a grizzly bear (in terms of 3D space) and preserve its catapult jumping system?

The only thing that need remain in terms of 'grasshopper-ness, or cricket-ness' is the catapult jumping system, and preferably a frightening insectoid appearance. It need not look at all like our starting-creatures.

  • Higher oxygen content in the air?
  • Sturdier body-plan (i.e. thicker carapace? Different materials? Wider joints/legs?)
  • Bird-bone-esque adaptation of weight to power? Or is this irrelevant with mostly slow-twitch muscle at the play in the catapult system?

I'm trying to think through a creature that relies on jumping and mechanoreception to hunt prey, and is somewhat frightening to behold.

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    $\begingroup$ You have a problem here, it's that the square/cube law isn't so much a "basic physiological constraint" as a basic physics constraint, no physiological changes will give you the same "jump/body" ratio". $\endgroup$
    – Pelinore
    Mar 16 '20 at 11:51
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    $\begingroup$ @Adrian no they really don't scale linearly just fine, try dropping an ant from 100 feet, now try dropping a perfectly scale but giant 1 ton ant from the same height, now tell me these things scale just fine again. $\endgroup$
    – Pelinore
    Mar 16 '20 at 13:00
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    $\begingroup$ @AdrianColomitchi This is stuff you should know from secondary school, Google it $\endgroup$
    – Pelinore
    Mar 16 '20 at 14:01
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    $\begingroup$ @AdrianColomitchi Its a pretty simple law. The cross sectional area of a muscle gets squared, which is proportional to strength. The weight it needs to lift gets cubed (volume) because real things aren't purely 2D. So your square your strength and cube the weight you need to lift. So as you increase the size, the weight will naturally increase faster than your strength and lower all strength related ratios. $\endgroup$
    – Shadowzee
    Mar 17 '20 at 1:03
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    $\begingroup$ Nope just won't work, sorry, see @Shadowzee's summary of the square cube law, the bigger it gets the more muscle it needs to achieve the same distance jump (note: the same distance proportional to its body size is further than that) & the more muscle it has the bigger it gets, even the most exotic of materials won't be enough to fully get around that. $\endgroup$
    – Pelinore
    Mar 17 '20 at 18:41
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I'd go with:

  1. a composite exoskeleton - layers of highly compressive-resistant materials between layers of elastic ones; or highly elastic on compression and high tensile will do the same - is something needed to be elastic and diffusive (spread the energy/tension over higher area) enough to mellow the take-off/landing shocks while still conserving/converting as much energy as possible (e.g landing recover some energy required for the next jump).
    Two YouTube down-to-Earth-engineering clips that deal with composites for hardening and elasticity: fiber glass strengthening and core composites

  2. elastic and tough "tendons" that allow storing mechanical energy to be used in the jump - and maybe replenished over a longer time. That is, it would be easier if the creature doesn't keep kangaroo-style hopping but taking some time to prepare for the jump (like grass-hoppers do)

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