Tooth Shape Controls Stiffness and Food Collection Efficiency in Biomimetic Radular Teeth

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The work titled "Tooth Shape Controls Stiffness and Food Collection Efficiency 2
in Biomimetic Radular Teeth" by Wencke Krings and the Colleagues, is an example a thorough and very detailed biomimetic study on the effectiveness of model spekia zonata biomechanical systems of radula teeth, working in a gel-type milieu, for efficiently being fed from the nearby environment. 

To be more specific, on the one hand, the radula facilitates mechanical interaction with foods and substrates over a broad range of material properties (e.g., hardness, stiffness) and structure such as  the ones at the edge of smooth vs rough or compact vs. porous circumstances, helping to achieve some trophic diversification and/or niche specialization. 

On the other hand, in turn, such work–yield decoupling points to the fact that energy was permanently dissipated into certain loss-indicating and unnecessary processes such as poroelastic compression, friction, sliding or elastic deformation rather than the affordable signatures of always-needed penetration and cutting. 

Therefore, since this work is also about negative (due to unnecessary dissipation of mechanical work) influence(s) of poroelastic compression, friction, sliding, etc., expected to occur at the radula vs gel interface, it is proposed to slightly extend this useful thought by including, and properly introducing, some additional references: 

An appropriate recent review on porous media: https://www.mdpi.com/1996-1073/14/23/8114, 
with an emphasis put on a hydration of a soft-material system: https://jp2.journaldephysique.org/articles/jp2/abs/1996/11/jp2v6p1537/jp2v6p1537.html (not obligatory to reference but included here in order to uncover the reviewer's reasoning) plus friction addressing another biophysical reference, offered on the same basis: https://link.springer.com/article/10.1134/S0006350915060093. (The present reviewer is of the  opinion that elaborating slightly more the issue of porosity vs. viscoelasticity, and friction as applied to active matter would distinctly enrich the clarity of the message of this otherwise excellent paper. 

As for the small technical corrections: on p. 4, subsec. 2.4 concerning the bending test, the authors applied the load at 400 g, 0.245 N but why not slightly higher in value, because the applied weight is going to be slightly less than 0.4 N? As for Figures, Fig. 1 likely conains a misprint "linare"? Moreover, what does it mean (subsec. 4.4) 'engagement mechanics' - it seems to be out of standard biomechanical nomenclature or is it appropriate to employ? 

In spite of the mentioned small "imperfactions" of the reviewed ms. it ought to be ascertained that it is a well-elaborated, and conducted in versatile as well as interesting ways study to be recommended for publication, with possibly a minor revision to be performed by the Authors. 

Author Response

Reviewer 1:

Open Review

(x) I would not like to sign my review report

( ) I would like to sign my review report

Quality of English Language

( ) The English could be improved to more clearly express the research.

(x) The English is fine and does not require any improvement.

 

	Yes	Can be improved	Must be improved	Not applicable
Does the introduction provide sufficient background and include all relevant references?	( )	(x)	( )	( )
Is the research design appropriate?	(x)	( )	( )	( )
Are the methods adequately described?	( )	(x)	( )	( )
Are the results clearly presented?	(x)	( )	( )	( )
Are the conclusions supported by the results?	(x)	( )	( )	( )
Are all figures and tables clear and well-presented?	( )	(x)	( )	( )

 

The work titled "Tooth Shape Controls Stiffness and Food Collection Efficiency in Biomimetic Radular Teeth" by Wencke Krings and the Colleagues, is an example a thorough and very detailed biomimetic study on the effectiveness of model Spekia zonata biomechanical systems of radula teeth, working in a gel-type milieu, for efficiently being fed from the nearby environment. 

• Thank you very much for this positive assessment. We greatly appreciate your recognition of our work. Your encouraging feedback is highly valued.

To be more specific, on the one hand, the radula facilitates mechanical interaction with foods and substrates over a broad range of material properties (e.g., hardness, stiffness) and structure such as the ones at the edge of smooth vs rough or compact vs. porous circumstances, helping to achieve some trophic diversification and/or niche specialization. 

On the other hand, in turn, such work–yield decoupling points to the fact that energy was permanently dissipated into certain loss-indicating and unnecessary processes such as poroelastic compression, friction, sliding or elastic deformation rather than the affordable signatures of always-needed penetration and cutting. 

Therefore, since this work is also about negative (due to unnecessary dissipation of mechanical work) influence(s) of poroelastic compression, friction, sliding, etc., expected to occur at the radula vs gel interface, it is proposed to slightly extend this useful thought by including, and properly introducing, some additional references: 

An appropriate recent review on porous media: https://www.mdpi.com/1996-1073/14/23/8114, 
with an emphasis put on a hydration of a soft-material system: https://jp2.journaldephysique.org/articles/jp2/abs/1996/11/jp2v6p1537/jp2v6p1537.html (not obligatory to reference but included here in order to uncover the reviewer's reasoning) plus friction addressing another biophysical reference, offered on the same basis: https://link.springer.com/article/10.1134/S0006350915060093. (The present reviewer is of the opinion that elaborating slightly more the issue of porosity vs. viscoelasticity, and friction as applied to active matter would distinctly enrich the clarity of the message of this otherwise excellent paper. 

• We thank the reviewer for this helpful suggestion. We have expanded the discussion to explicitly address energy dissipation mechanisms underlying the observed work–yield decoupling.

As for the small technical corrections: on p. 4, subsec. 2.4 concerning the bending test, the authors applied the load at 400 g, 0.245 N but why not slightly higher in value, because the applied weight is going to be slightly less than 0.4 N?

• We thank the reviewer for pointing this out. The force value given in the manuscript was incorrect and has been corrected. A load of 400 g corresponds to approximately 3.92 N (m·g), not 0.245 N. The text and the Supplementary has been revised accordingly.

As for Figures, Fig. 1 likely conains a misprint "linare"?

• Thank you. Changed accordingly.

Moreover, what does it mean (subsec. 4.4) 'engagement mechanics' - it seems to be out of standard biomechanical nomenclature or is it appropriate to employ? 

• Thank you. We changed it to contact mechanics.

In spite of the mentioned small "imperfactions" of the reviewed ms. it ought to be ascertained that it is a well-elaborated, and conducted in versatile as well as interesting ways study to be recommended for publication, with possibly a minor revision to be performed by the Authors. 

• Thank you so much for your time and work!

Reviewer 2 Report

Comments and Suggestions for Authors

Review of biomimetics-4232328 entitled “Tooth Shape Controls Stiffness and Food Collection Efficiency in Biomimetic Radular Teeth” by Krings et al.

1. This is an interesting and well written manuscript about a study involving physical models of gastropod taenioglossan radular teeth. The experimental study was nicely designed and executed. The manuscript clearly explains the hypotheses, how they were tested, and how the results were analyzed.
2. The Supplemental materials include many figures that nicely show the morphology of the 3D printed teeth (which look highly detailed). However, neither the main manuscript nor the supplements clearly explain the 3D printed material except for “UV-curable resin.” I would like the authors to share as much information as possible about the this precise kind of resin, both in terms of chemistry/material, and in terms of material property (what stiffness, flexibility, etc.). I think these details are really important in terms of understanding the experiments and their results.
3. The figures are nice, but in Figure 4 the four bright colors in the legend do not match the actual colors shown in the plot. Please either change the colors in the small legend (or the plot itself) so that these clearly match, or else simply label, by name, the four overlapping “clouds” showing the work vs gel removal.
4. The JMP Pro 17 mentions that this comes from SAS Institute Inc. in Cary, USA. Please clarify that this comes from Cary, NC (=North Carolina), as there are many cities named Cary in different states of USA.
5. I like (and agree with) the authors’ overall conclusions in lines 388-390 that feeding “requires controlled stiffness combined with limited compliance,” and that “stiffness alone does not guarantee high removal” (line 441). Yes—there are several complex factors at work here. Finally, I appreciate the recognition (lines 584-586) that central teeth likely play a role mainly in spacing other teeth rather than removing food.
6. The writing overall is excellent: clear and detailed. However, in at least one place (line 506) the writing is awkward (“together with the here presented one”). Why not simply say something like “together with data presented here” or “with these new data,” etc.?

Author Response

Reviewer 2:

Open Review

( ) I would not like to sign my review report

(x) I would like to sign my review report

Quality of English Language

( ) The English could be improved to more clearly express the research.

(x) The English is fine and does not require any improvement.

 

	Yes	Can be improved	Must be improved	Not applicable
Does the introduction provide sufficient background and include all relevant references?	(x)	( )	( )	( )
Is the research design appropriate?	(x)	( )	( )	( )
Are the methods adequately described?	(x)	( )	( )	( )
Are the results clearly presented?	(x)	( )	( )	( )
Are the conclusions supported by the results?	(x)	( )	( )	( )
Are all figures and tables clear and well-presented?	(x)	( )	( )	( )

 

Efficiency in Biomimetic Radular Teeth” by Krings et al.

1. This is an interesting and well written manuscript about a study involving physical models of gastropod taenioglossan radular teeth. The experimental study was nicely designed and executed. The manuscript clearly explains the hypotheses, how they were tested, and how the results were analyzed.

• Thank you so much for your time and comments!

1. The Supplemental materials include many figures that nicely show the morphology of the 3D printed teeth (which look highly detailed). However, neither the main manuscript nor the supplements clearly explain the 3D printed material except for “UV-curable resin.” I would like the authors to share as much information as possible about the this precise kind of resin, both in terms of chemistry/material, and in terms of material property (what stiffness, flexibility, etc.). I think these details are really important in terms of understanding the experiments and their results.

• Thank you. Added accordingly.

1. The figures are nice, but in Figure 4 the four bright colors in the legend do not match the actual colors shown in the plot. Please either change the colors in the small legend (or the plot itself) so that these clearly match, or else simply label, by name, the four overlapping “clouds” showing the work vs gel removal.

• Thank you: Changed accordingly.

1. The JMP Pro 17 mentions that this comes from SAS Institute Inc. in Cary, USA. Please clarify that this comes from Cary, NC (=North Carolina), as there are many cities named Cary in different states of USA.

• Thank you. Added accordingly.

1. I like (and agree with) the authors’ overall conclusions in lines 388-390 that feeding “requires controlled stiffness combined with limited compliance,” and that “stiffness alone does not guarantee high removal” (line 441). Yes—there are several complex factors at work here. Finally, I appreciate the recognition (lines 584-586) that central teeth likely play a role mainly in spacing other teeth rather than removing food.

• We thank the reviewer for this encouraging comment and for highlighting these key conclusions. We agree that the results point to a complex interplay between stiffness, compliance, and tooth geometry.

1. The writing overall is excellent: clear and detailed. However, in at least one place (line 506) the writing is awkward (“together with the here presented one”). Why not simply say something like “together with data presented here” or “with these new data,” etc.?

• Thank you. We went over the text again.