But, the conclusions need to be more succinct. This may require the authors to re-state their case and probably re-define the central message of the paper. Then I expect the authors to see the proposed revision as an opportunity to accomplish a nice text that has broader appeal, but at the same time moves the field forward. However, as noted above, I have quite frequently seen whales breach far from their low-latitude winter breeding grounds. Also, the tagging locations listed at the start of the Materials and methods section makes clear that many of the tags were deployed in locations e.
I also realize this is somewhat species-specific. For example, I don't think I've ever heard of gray whales breaching in feeding areas, though know gray whales breach in breeding grounds.
In contrast, breaching in feeding grounds is quite common for humpback whales. I'm not necessarily disputing the authors' contention that breaching is an important signaling phenomenon that is important in breeding groups, but I worry a bit that readers less familiar with field observations of whales might conclude that breaching occurs primarily or solely on breeding grounds. I am sure the authors don't believe this, and I'm not saying they mean to say this, but I think a less-educated reader might unfortunately conclude this.
I urge the authors to think about this point and address it in some way. However, I wonder if it would be useful for the authors to list and explain, in a bit more but not extensive detail early on in this manuscript, some of the other possibilities that have attracted scrutiny.
Specifically, I wonder if the authors might comment on the possibility that breaching might sometimes be related to parasites, either as a behavioral means to detach ectoparasites or as a result of endoparasites in whale ears or sinuses, etc. I think the authors should not ignore this idea because they specifically note that a "breach was likely a response to tagging, since it occurred immediately after the deployment.
The Introduction explains that female sperm whales "regularly breach" whereas larger males "breach very infrequently.
And yes, I understand that Figure 6 directly shows the influence of body mass in humpbacks. Do the authors know anything even from previous studies by other scientists about whether shorter, younger individuals of the biggest whale species occasionally breach? Do younger whales e. Is there any correlation between exit pitch and roll angle? I know rolling has been studied extensively in spinner dolphins e. I wonder how long it takes a whale to "recover" after breaching.
I have seen a humpback whale breach twice in rapid succession I am sure it was the same whale. Does the tag data analyzed for this study tell anything about how much or how little time whales take between multiple breaches? I expect the data from the three very active juvenile humpbacks that breached times might reveal something about this behavior's relation to limits from muscle vs. I thought the figure was showing information about variation in breaching costs and speed with increasing body size in a general sense e.
The text doesn't help a lot. The questions are stated in a logical order as the answer to the first one is needed to answer the second, which, in turn, needed to answer the last. Nonetheless, I am not satisfied with the answers to the last two questions — I would have expected a sharper message from an eLife paper. For example, there is a long verbal description of breaching trajectories. Given the figure on which these trajectories are displayed, I do not need this description.
I am afraid that vital information can be easily lost between too many words. What is the difference between a feeding event and a partial breach?
Because a feeding event can be an excellent unit of energy — at least for humpback whales — it has to be defined and the respective trajectories shown for comparison. The two estimates suggested in the paper differ for a ton whale by more than an order of magnitude!
I suggest leaving it out of the paper. An energy expenditure in a single feeding event I am talking about mechanical energy only is a much better unit. An average amount of energy in a single gulp is a good unit as well. For me it is an inseparable part of the event. The answer here will affect the conclusion of this study. Is it? First, define the drag. CD is a weak function of speed. Your equation 8 sets it. There is no need to write it explicitly thereafter. Next, write the Newton second law.
The added mass is negligible as compared with the real mass, and considering estimation uncertainties, can be safely ignored. The expression on the left is the mechanical energy spent; the integral on the right can be evaluated numerically D is a function of v only without any additional assumptions. After all, the speed is known at every instant. The write-up in the paper needs not be longer than this comment. It is counterproductive to explicate constants in an equation, especially if they are empirical.
As mentioned in the paper itself, drag can be divided into viscous friction drag and pressure drag. The former is practically independent on the shape of the body, whereas the latter can increase only if body flex induces flow separation. There is no evidence that flow separation occurs over swimming fishes, and therefore an increase in drag is unjustified.
Liu, Barazani, Triantafyllou are just a few gentlemen that were working on this in the last 15 years. I suggest revising. I am skeptical about using an acceleration signal for speed measurement after it has been down-sampled to 25 and possibly less HZ. The method was designed with turbulence noise in mind, and this frequency seems too low to be effectively associated with it Adding a supplementary on speed calibration may help.
Figure 6 is hardly convincing. We thank the reviewers and the editor for the positive comments, and we agree that the conclusions could be clarified to better express the central message of the manuscript. We have substantially revised the Discussion to directly answer the three questions that we propose in the Introduction and that we restate in the first paragraph of the Discussion. As the reviewer states in comment 11, these questions follow a logical order and must be answered sequentially to guide the reader through our thought process to the final conclusions of the paper.
We have also added a new panel to Figure 6 which presents the maximum mass-specific power and now allows the reader to sequentially follow along with the conclusions to question 3.
The first two paragraphs of the subheading entitled Does body size limit breaching performance? We appreciate the reviewer's concern and have made the following changes.
The Introduction has been changed to " since species with complex social structures breach frequently". The original intent of this sentence was to convey the idea that species with distinct breeding grounds have complex social structures, but this is a more direct way to say it.
We have also removed the reference to breeding grounds, where it does not add to the message of the paragraph. Also, to answer the reviewer's question, we have recorded several instances of gray whales breaching in the Puget Sound region although only one animal was tagged.
Good point: to provide some more background information on the hypothesized purposes of breaching we have added the following sentence:. Another, commonly held explanation is that in large whales, aerial displays are a form of social communication. We agree that this information is important, but are reluctant to explain the breach recorded from the gray whale as an attempt to remove the tag. The whale only breached once and then returned to a calm state, sitting near the bottom of the sound.
The deployment lasted for 17 hours and the whale made no further breaches or attempts to dislodge the tag. For this reason, we think that a more likely explanation for the breach was as a signal of displeasure. To answer the reviewer's question: male sperm whales use unique clicks that likely convey their size to other individuals.
Please see the next section regarding the use of breaching for signaling. We agree with the reviewer that the reason why certain species breach frequently is more complex than a simple physical argument.
Rather, it is more likely a combination of complex social structures and the abilities to breach that predispose certain species to incorporate breaching as a method of signaling. Species-level maneuverability also likely plays an important role, however, the comparative maneuvering abilities of large whales are currently poorly understood and remain somewhat anecdotal.
To clarify these issues we have changed the penultimate paragraph to:. This was our original intent, however we only had body length measurements for a small subset of the 28 tagged humpback whales. Figure 6 includes all of the whales with known body lengths and high-performance breaches in our dataset. There is some very sparse, anecdotal evidence that blue whale and fin whale juveniles can breach, albeit very rarely. Whitehead, , lists the propensity of large rorquals to breach as follows: blue — almost never; sei — almost never; finback — rare.
One of our co-authors J. Personally, I P. S was on a boat in a newly discovered breeding ground for blue whales when a juvenile blue whale breached, off in the distance. The entire crew was surprised by the event, and there was much discussion on whether that was actually a juvenile blue whale or something else. All this is to say that if juvenile blue, fin, and sei whales breach, it is a very rare event, and we agree with the reviewer that there is likely a combination of physical and species-level behavioral limitations on breaching.
We hope that we adequately addressed this in comment 4 and the associated changes to the manuscript. Yes, this is well documented by Whitehead, Wursig, and others and is one of the reasons for the hypothesis that breaching is a form of play, for juveniles.
We have addressed this in the same sentence that we addressed comment 2. The sample size of individuals and breaching events performed by whales of known dimensions was too low to be conclusive. Anecdotally from the videos, it seems as if juveniles add more long-axis rotation to their breaches which allows them to emerge from the water in a larger amount of configurations.
Meanwhile larger whales spin less often and smaller amounts and so when they emerge upside-down this is a direct result of the 'backflip'.
This is discussed briefly in the Discussion. We looked at this and there was no correlation between exit pitch and roll angle. The topic of breaching sequences has been studied extensively using traditional focal follow techniques including much of work from Whitehead and Wursig.
For one of the juveniles that we tagged, the shortest time between consecutive breaches was 6. The third juvenile breached intermittently. The scaling of recovery time with body mass is a worthwhile topic and would probably have some interesting implications, but we believe our dataset is too sparse to accurately pursue this due to the low number of whales with known body lengths, and low number multiple-breach sequences that could assure us of an accurate minimum time between events.
We added the following line as documentation of the time between consecutive breaches:. We have modified Figure 6 in response to comment 20 and updated the caption to:. C To attain the higher speeds required to emerge from the water, larger whales need to generate higher mass-specific power outputs or extend the duration of their trajectories green numbers.
We agree that the manuscript will be greatly improved by streamlined conclusions. Please see the response to the editor's notes for the detailed changes that we have made. We have substantially revised the concluding paragraph to directly answer the three questions that we propose, in a sequential manner designed to guide the reader to the central message of the paper.
As stated in comment 12, we have also moved a significant amount of the descriptive text in the results to a new table. We agree, and have converted that paragraph to a new table Table 2 in order to reduce the length of the text. This is a good point, and so we have added the trajectory of a feeding lunge to Figure 3, and added the following text:. The Field Metabolic Rate of large cetaceans has been difficult to quantify and remains somewhat controversial. As explained in the text, there are two main theories for how FMR scales with extreme body mass.
We agree that the two competing theories provide very different estimates, however, our results show that under both scaling regimes, the cost of breaching increases disproportionately with body mass.
We believe this result is important enough to warrant the paragraph that we devote to this topic also see Supplemental File 1A. We agree that the mechanical cost of lunging makes a good comparison for the cost of breaching. The mechanical cost of lunging can either refer to the pre-engulfment acceleration, or the pre-engulfment acceleration and the post-engulfment deceleration which includes acceleration of engulfed water.
If the goal is to compare the energetics cost of two events, the latter is appropriate. If the goal is to compare the energetic costs of two mechanically similar trajectories, then the former is appropriate. For this reason, we do compare the cost of breaching with the cost of the mechanically similar pre-engulfment acceleration phase of lunging Figure 6 and the old Table 2. This comparison did turn out to be very interesting because, while feeding lunges are generally considered to use 'high-performance' accelerating maneuvers, our results show that even high-speed lunges are relatively cheap compared to breaches and most lunges feature much slower speeds than the ones used for our comparison.
While we do agree that the energy contained in a single gulp would make a good alternative comparison for the cost of breaching, it is also subject to many uncertainties high variability in buccal cavity inflation, prey density, prey type, escape response. Meanwhile, its ecological relevance is not as straightforward as FMR. As described in the response to 14, this would represent a different way to compare energetic expenditure vs mechanical cost of lunging accelerations; energy contained in a gulp; or daily FMR.
We chose to focus on the mechanical cost of lunging pre-engulfment phase because this represents an accelerating trajectory similar to the accelerations used for breaching.
In the original version of this manuscript, the definition was presented earlier. Because we moved the Materials and methods section to the end of the manuscript to fit eLife 's formatting requirements, we have added the following clarification to the Results section:.
We appreciate the reviewer's suggestions for simplifying the explanation of the equations in the manuscript. The alternate method the reviewer describes is similar but not equivalent to the method that we use, since it relies on integrating the speed of the entire breaching trajectory. In contrast, our method uses the starting and ending velocities and requires deciding whether the breach follows a linear acceleration or a linear acceleration with a plateau.
Both methods result in similar results, although the numbers are not exactly the same. We did try the reviewer's suggestion but upon further consideration, our method allows the reader to use the values from Table S1 to recreate our results. Our method also allows for simple, theoretical trajectories to be constructed see blue line in revised Figure 6A-C, the maximum power calculations for the new panel Figure 6C, and the analysis of theoretical blue whale breaching velocities.
For these reasons we would like to keep our analysis in its current form. Additionally, although our derivation is lengthy, we believe that providing it is important for allowing the readers to evaluate the final form of the equation. Originally, the derivation was located in the supplementary section, but we moved it to the main text to conform with eLife 's format.
We also agree that providing the coefficient of drag as a constant would be simpler, however, in our equations Cd is dependent on the Reynolds number and thus, the velocity. Therefore, to perform the integration, Cd must be expanded. After equation 27, Cd final can be substituted back in, but that would require including an additional equation. We would be happy to move the derivation to a Mathematical Model section after the Materials and methods section, if the eLife format permits.
Such doubling was based on the work by Frank Fish on the hydrodynamics of fluking odontocetes Fish, , Here Fish used kinematic measurements to calculate the value of the fluking thrust based on the lunate tail thrust-efficiency modeling of Chopra and Kambe, , and Yates, The results yielded drag coefficients that ended up at 2 to 3 times higher than the drag estimated for same-area flat plates in longitudinal low, a finding that turned out in agreement with similar drag and thrust studies of fish Blake, , pp.
Chopra, M. Hydrodynamics of lunate-tail swimming propulsion. Part 2. Fluid Mech. Yates, G. Hydrodynamics of body and caudal fin propulsion. In Fish Biomechanics ed. Webb and D. Weihs , pp. New York: Praeger. Schultz, William W. Integrative and Comparative Biology. For the humpback breaches used for the scaling analysis we used the accelerometer vibration method performed on the full-resolution, Hz data.
We apologize for not clarifying this previously, and have made the following change to the text L The method is exactly as described in Cade et al. We revised Figure 6 to include the speed and cost of idealized breaches performed with uniform trajectories across the range of humpback body sizes. The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
We thank Megan Jensen for her ideas, efforts in the inception of this paper, and her initial data analysis. This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose.
The work is made available under the Creative Commons CC0 public domain dedication. Article citation count generated by polling the highest count across the following sources: Crossref , PubMed Central , Scopus.
A whale leaping above the surface expends an enormous amount of energy, displaying its health and strength to peers and potential mates. Phagocytosis requires rapid actin reorganization and spatially controlled force generation to ingest targets ranging from pathogens to apoptotic cells. How actomyosin activity directs membrane extensions to engulf such diverse targets remains unclear. Maybe you will see a breaching humpback on your tour with us?
Go back. Which are the most common whales? Learn more about the whales. Humpback Whales breach to communicate a desire or a need 2 2. Whales breach to let others know about a nearby predator 3 3. Whales breach to observe what goes on around them 6 Join a Tour to see the Humpback Whales 6. Check out these interesting articles:. Snorkeling vs Scuba Diving - Underwater discovery. Discover Scuba Diving course, Get ready to go into a new world.
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