Control strategies of gecko’s toe in response to reduced gravity

Round 1

Reviewer 1 Report

An interesting work.

line 189 and 190 need to be removed in the final version.

Why only 6 animal samples have been taken for the experiment? Any particular concern.?  

Author Response

line 189 and 190 need to be removed in the final version.

A: Thanks for your review. We correct it in updated M.S.

 

Why only 6 animal samples have been taken for the experiment? Any particular concern.?  

A: Thanks for your review. Although only 6 animals, we got more than 50 samples. I think it is enough.

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript describes experiments on the adaptations of a gecko's movement of its feet and toes in response to an effective reduction in its weight. An novel device is described where forces arising from the placement and movement of the gecko's feet can be measured in three directions. The experiments appear to be carefully done and the results are interesting, showing that the gecko can adapt to a different situation. I have a few comments I would like the authors to address before this article can be accepted for publication in Applied Sciences.

1) The concept of "reduced gravity" that is used in the title and in several places in the manuscript does not really apply. Gravity is the same everywhere in the experimental setup. Rather, the authors have reduced the gecko's effective weight by counterbalancing the normal force arising from its body weight. The experiment should be described a such.

2) How do the results compare to the situation where the gecko would be walking/running on the ceiling (i.e., upside down)? This should require an even more extreme adaptation of the toe/foot position. It could be studied with the current setup by just attaching a bigger balloon to the gecko, trying to pull it off the surface. (This suggested experiment further emphasizes that the current experiment involving balloons is not done at "reduced gravity" but at a different normal force than when walking/running on the ground.)

3) On p. 6, lines 199 and 203, the authors claim that "both the shear force and normal force follow Amontons' law". This statement is confusing since Amontons' law describes (among other things) a constant RATIO of the shear force to the normal force. That is, the normal force alone cannot be said to follow Amontons' law. Rather, if the shear force is proportional to the normal force, the SYSTEM follows Amontons' law.

4) There are a couple of small typos: "peek" should probably be "peak" in several places. One line of text under eq. (2) seems like a comment that should be removed: "the text following an equation need not be a new paragraph..."

Author Response

1) The concept of "reduced gravity" that is used in the title and in several places in the manuscript does not really apply. Gravity is the same everywhere in the experimental setup. Rather, the authors have reduced the gecko's effective weight by counterbalancing the normal force arising from its body weight. The experiment should be described a such.

A: Thanks for your review. Yes, it should be “simulated reduced gravity”. We correct it in part 2.4 : The gecko's effective weight was reduced by counterbalancing the normal force arising from its body weight.

2) How do the results compare to the situation where the gecko would be walking/running on the ceiling (i.e., upside down)? This should require an even more extreme adaptation of the toe/foot position. It could be studied with the current setup by just attaching a bigger balloon to the gecko, trying to pull it off the surface. (This suggested experiment further emphasizes that the current experiment involving balloons is not done at "reduced gravity" but at a different normal force than when walking/running on the ground.)

A: Thanks for your review. Yes, it will be addressed in further work.

 

3) On p. 6, lines 199 and 203, the authors claim that "both the shear force and normal force follow Amontons' law". This statement is confusing since Amontons' law describes (among other things) a constant RATIO of the shear force to the normal force. That is, the normal force alone cannot be said to follow Amontons' law. Rather, if the shear force is proportional to the normal force, the SYSTEM follows Amontons' law.

A: Thanks for your review. We correct it: the shear force is proportional to the normal force with a coefficient of 0.31.

 

4) There are a couple of small typos: "peek" should probably be "peak" in several places. One line of text under eq. (2) seems like a comment that should be removed: "the text following an equation need not be a new paragraph..."

A: Thanks for your review. We correct it

Author Response File: Author Response.docx