How can whales jump

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. Here, we combine lattice light-sheet microscopy LLSM with microparticle traction force microscopy MP-TFM to quantify actin dynamics and subcellular forces during macrophage phagocytosis. We show that spatially localized forces leading to target constriction are prominent during phagocytosis of antibody-opsonized targets.

Contractile myosin-II activity contributes to late-stage phagocytic force generation and progression, supporting a specific role in phagocytic cup closure. Observations of partial target eating attempts and sudden target release via a popping mechanism suggest that constriction may be critical for resolving complex in vivo target encounters. Overall, our findings present a phagocytic cup shaping mechanism that is distinct from cytoskeletal remodeling in 2D cell motility and may contribute to mechanosensing and phagocytic plasticity.

Key processes of biological condensates are diffusion and material exchange with their environment. Experimentally, diffusive dynamics are typically probed via fluorescent labels. However, to date, a physics-based, quantitative framework for the dynamics of labeled condensate components is lacking. Here, we derive the corresponding dynamic equations, building on the physics of phase separation, and quantitatively validate the related framework via experiments.

We show that by using our framework, we can precisely determine diffusion coefficients inside liquid condensates via a spatio-temporal analysis of fluorescence recovery after photobleaching FRAP experiments. We showcase the accuracy and precision of our approach by considering space- and time-resolved data of protein condensates and two different polyelectrolyte-coacervate systems.

Interestingly, our theory can also be used to determine a relationship between the diffusion coefficient in the dilute phase and the partition coefficient, without relying on fluorescence measurements in the dilute phase. This enables us to investigate the effect of salt addition on partitioning and bypasses recently described quenching artifacts in the dense phase.

Our approach opens new avenues for theoretically describing molecule dynamics in condensates, measuring concentrations based on the dynamics of fluorescence intensities, and quantifying rates of biochemical reactions in liquid condensates. Cited 7 Views 2, Annotations Open annotations. The current annotation count on this page is being calculated. Cite this article as: eLife ;9:e doi: Figure 1. Download asset Open asset. Figure 2. Figure 3. Table 1. Table 2. Trajectory Starting location Characteristics Species events U-shape surface horizontal acceleration slightly below the surface; rapid upward pitch change to emerge from water Whitehead, a humpback 1 humpback, juv.

Figure 4. Figure 5. Figure 6. Table 3. Video 1. Download asset. Download as MPEG Download as WebM. Download as Ogg. The trajectory of this breach is shown in Figure 2. Abe T Sekiguchi K Why does the ocean sunfish bask? Dudley R Milton K Parasite deterrence and the energetic costs of slapping in howler monkeys, Alouatta palliata Journal of Mammalogy 71 — Fish FE Wing design and scaling of flying fish with regard to flight performance Journal of Zoology — Fish FE Power output and propulsive efficiency of swimming bottlenose dolphins Tursiops truncatus.

Fish FE Comparative kinematics and hydrodynamics of odontocete cetaceans: morphological and ecological correlates with swimming performance. In: Castelini M. A, Mellish J. CRC Press. In: Norris K. S, editors. Whales, Dolphins, and Porpoises. Berkeley: University of California Press.

Lockyer C Growth and energy budgets of large baleen whales from the southern hemisphere. Series B: Biological Sciences — Webb PW The swimming energetics of trout. Webb PW Hydrodynamics and energetics of fish propulsion.

Weihs D Dynamics of dolphin porpoising revisited Integrative and Comparative Biology 42 — Whitehead H a Humpback whale breaching. With larger whales, like the Humpback, breaching frequency also appears to increase with wind speed.

One hypothesis is that, with a noisy ocean surface, a breach may provide a form of communication that can be better dispersed and received by other whales in multiple directions.

In fact, it has been observed that the whales breach more often when their associates are further away, at least 2. In addition, if the waters are particularly choppy, a breach may give a large marine mammal the chance to breath in air that is free from spray. Another reason for Humpback Whales, and Baleen Whales in general, to breach is to remove some pesky hitchhikers.

It is not uncommon for Humpback Whales to be riddled with barnacles and lice and, although not harmful to the whale, too many could be annoying so a jump can be a cleansing event. Breaching events have been linked to communication, with social species jumping more frequently. Propositions include aggression, annoyance, vigor of a male, and courtship behavior. A jump can also be used to add emphasis to a signal already made: vocal or visual, indicating a desire or a need. Turning our attention back to Killer Whales, a good time to see them leaping out the water is during a hunt.

Air is times less dense than water and so a jump gives the Killer Whale a good advance on its prey. This high-speed leap is known as porpoising and even once the feeding event is over, jumping can take place as a social form of celebration. In particular, jumping behavior by young ones in the pod, with no conceivable purpose, may simply be practice for the future. Killer Whales have terrific eyesight both above and below the water so popping its head out could be the animal observing its surroundings, looking for other members of its pod or seeing if there is any food around.

However, for Whales lower down the food chain a breach may actually be a signal that there are predators around rather than a signal where the food is. What we can be pretty certain about is that they do not do it to entertain us humans but for some purpose beneficial to their survival. It takes a certain combination of circumstance, mood, timing and luck to see a whale jump. But of course, when it happens it is truly a magical and humbling experience.

Read More Articles , News. News Articles Sightings Contact Us. In order to lunge out of the water, a whale usually uses one of two techniques. The first, often done by sperm and humpback whales, involves swimming vertically at the surface from a deep depth and breaking the surface at a perpendicular.

A whale needs to swim about 18 miles per hour in order to get 90 percent of his body out of the water. The other technique is to swim fast and close parallel to the surface, and then turn sharply to pop out of the water. Though breaches certainly look spectacular, they may serve a purpose, too. One theory suggests that breaching could be done as a form of social communication. It could be used to assert dominance, to court a potential mate, or simply to alert another whale to your presence.