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I live in Colorado Springs, Colorado, USA and I have noticed something interesting while walking and longboarding the many miles of paths of trails in the city. Grasshoppers seem to get stuck quite frequently in sideway cracks. I see this rather frequently, sometimes multiple times in a single walk, in certain areas, during the day. This alone is not interesting, but I suspect it I suspect that at least one of them may have jumped out of their leg, if you will. I'll explain.

First, I am reasonably sure they are stuck, because I can see them try to get away from me, while one leg remains fixed in the crack. Also, I see countless more (sometimes several dozens in those same areas), that appear to have been stuck, but have since been run over by something (bike, scooter, skateboard, etc.) or stepped on. I see VASTLY more grasshoppers smashed on cracks in the sidewalks, than on the flat surfaces of the paths. I counted a small (maybe 100-200 meters, I admit I am bad at estimating distance) stretch of path and counted over 25 smashed in cracks and only 6 on that flat surfaces. And, obviously, the cracks represent only a small fraction of the total area of pavement. So, as I said, I am reasonably sure they are getting stuck. That being said, it is possible the reason so many grasshoppers get killed in the cracks is due to something else. An example I can think of is that they seek nutrients filled within the cracks. Of course, I am not sure why they would be attracted to the cracks, considering the extreme danger, when they are surrounded by vegetation. Are grasshoppers smart enough to recognize a busy and dangerous pathway through their territory? IDK.

However, if they are getting stuck, could they jump out of their legs? My evidence for that is a lot more sparse. I have only a handful of possible clues. First, I have seen a few (maybe 4 or 5) incidents in which the leg was mangled. In a couple, the leg seemed to be dislocated and nonfunctional; the grasshopper would scurry using its other limbs while the nonfunctional leg was stuck, immobile, in the crack at an odd angle. A couple other times I saw what looked to be a pinkish-white "meat" (maybe coagulated blood?) popping out around where the "hip" was, where the leg connected to the thorax. That was on much bigger grasshoppers (like 4"-6" in length).

Finally, a couple days ago, I was walking again and I looked in a crack and I found what I believe to be a grasshopper leg. I pulled the leg out, and I thought it appeared to be missing the foot, so I guessed it was stuck in the crack. I did not have my phone at the time, so I could not take a picture, and I did not even think to bring it home. I just tried to memorize what it looked like, then when I got home, I looked up grasshopper anatomy and I found this GRASSHOPPERS OF WYOMING AND THE WEST by the University of Wyoming. Judging by that drawing on the leg anatomy, the tarsus (everything from the spur down) was missing.

Anatomy of grasshopper hindleg

I never planned on asking a stack question, I just let it go until a friend in California mentioned seeing a grasshopper stuck in a crack in Hacienda Heights, California, USA. I do understand there could be other, good explanations for why a grasshopper's leg was left stuck in a crack, such as predation, but from what I remembered, there was that pinkish-white stuff showing at the coxa, so the predator took it off cleanly at the joint, or at least it seemed. I don't know if it was the coxa or just something protruding out of the trochanter after the coxa was ripped off. Or it could have been something protruding from the coxa, I just remember the end tapering down like that in the picture with the reddish-white stuff coming out.

In order to answer whether or not a grasshopper could jump out of its leg, I believe we need to know two things: 1) the amount of force produced by a grasshopper during a jump; and 2) the breaking strength of a grasshopper leg. The first was rather easy. Now, this does come from a University in the UK, (St. Andrews), but I imagine the grasshoppers in America are somewhat similar regarding the amount of force they can produce. If I am wrong about this, please correct me. The figure it gives is about 30 g (which I believe is grams-force and not the unit of acceleration). I am not sure if this is even the correct figure to use, because I am not sure this is the stress the leg feels, or if this is the right unit of measure for reasons I will explain. Even if this is the right figure, is this enough to break a leg off? What does it take to break off a grasshopper's leg?

Well, that is pretty much the question I need answered. I Googled variations of "breaking strength of grasshopper legs" using different variations and synonyms, and the most relevant of which brought up an NIH National Library of Medicine paper Fracture toughness of locust cuticle. The abstract says,

Our results show that the fracture toughness of cuticle in locust hind legs is 4.12 MPa m(1/2) and decreases with desiccation of the cuticle.

Can someone explain what that measurement is? I type "4.12 MPa m(1/2)" into Google, and this comes up:

The alleged answer to "4.12 MPa m(1/2)"

Is this the conversion to something? How does this play into the 30 grams force that is possible to be produced to by grasshoppers?

Also of note, I found an article on JSTOR (which frustratingly I cannot read, despite having JPASS) which on the Google search page has the following quote:

The grasshopper's leg muscles are so powerful that at maximum tension they can snap the tendons like threads.

Which is also quoted verbatim here without attribution: How strong are grasshoppers? - About Bugs.

One final thing before I summarize, I realize that if a leg were in a degraded state, such as after several attempts at jumping with a limb stuck in the crack, as well as possibly moving around, twisting it, breaking it more, it would take less force, and how much less would depend on the state of degradation. But, would jumping alone be enough to rip its leg clean off?

Okay, so the questions are:

Can a grasshopper jump with such force that it rips a stuck hindleg off, even after repeated attempts?

In order to answer that I believe knowing the answers to some other questions will help :

  1. How should the force applied to the joints of a grasshopper during a jump be measured?

  2. Is the amount of force produced on the ground during a grasshopper's jump, the same as the amount of force experienced on the legs of the grasshopper?

2a) If the legs experience a different force, what forces do they experience?

  1. What is the measurement of force on the ground in the St. Andrews paper? grams-force, g's, something else?

  2. I found that fracture toughness, mentioned in the NIH abstract is measured in Pascal m^(1/2) (pascal square root meter) not just m(1/2). But is this the measurement needed to determine the breaking strength of the leg. I THINK that would be tensile strength, but that is a wild guess.

  3. Could repeated jumping attempts reduce the leg's strength so much as to be ripped off?

5a) Any idea how many jumps it would take to finally rip it off?

5b) Is a grasshopper capable of this effort?

Any help anyone could give would be awesome. This is something I think about whenever I see these poor creatures grasped by what appears to be death's maws. Kinda breaks my heart a little when I see them. Anyways. Thanks.

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  • $\begingroup$ 4.12 MPa m(1/2) is a textual rendering of $4.12\, \text{MPa}\, \text{m}^{1/2}$. You can guess it from other units where m(-2) appears, and you can read it properly written in the actual pdf article. MPa is of course megapascal. journals.biologists.com/jeb/article/215/9/1502/11309/… $\endgroup$
    – Gae. S.
    Sep 21, 2023 at 8:40
  • $\begingroup$ Yeah, I figured that out when I put that text in Wolfram Alpha. It made more sense. Thank you for that article. $\endgroup$ Sep 21, 2023 at 16:46

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