Dolphin Swimming Research Articles

Response of Guiana dolphins to the construction of a bridge in Ilhéus, Northeastern Brazil.

This study aimed to investigate whether the use of space and movements of Guiana dolphins were altered during the construction of a cable-stayed bridge at the mouth of the Cachoeira River estuary in Ilhéus, Brazil. We described and compared the visitation rate, use of space, and movements of the Guiana dolphins across two periods: before the construction began (2015-2016) and during the construction of the bridge (2017-2020). A theodolite and a total station were used to observe and record the trajectories of the dolphins. From these trajectories, we estimated the Utilization Distribution (UD) using the biased random bridge kernel (BRBK) method, the area of use, and the core area, based on the 95% and 50% BRBK density, respectively. The dolphins did not change their visitation frequency to the estuary. No significant change in area fidelity was identified by comparing the overlap of areas used during two-month periods. No change occurred in the velocity and linearity of the trajectories of the dolphins swimming close to the bridge. However, contrary to expectations, the results indicated an increase in the use of areas close to the bridge during its construction. This may have been caused by the change in the distribution of their prey in the estuary due to the emergence of a sandbank near the bridge. Bridge construction work seems not to have directly affected the Guiana dolphins' use of the area, but the impact of the construction on the local topography has changed their areas of use and core areas of activity.

Drag reduction and locomotory power in dolphins: Gray's paradox revealed.

For 88 years, biologists and engineers have sought to understand the hydrodynamics enabling dolphins to swim at speeds seemingly beyond their energetic capabilities, a phenomenon known as Gray's paradox. Hydromechanical models calculating the drag of swimming dolphins estimated power requirements for sustained high-speed swimming, which were physiologically impossible. Using an uncrewed aerial vehicle, we calculated the total power of free-ranging dusky dolphins (Lagenorhynchus obscurus) at speeds from 0.9 to 6.9 m s-1, deriving drag coefficients (Cd) and drag. Our results showed that the Cd decreased exponentially with speed, reducing drag by up to 89% at speeds >2 m s-1, with an additional 17% reduction during porpoising (>4.0 m s-1). At 6.9 m s-1, drag was 32 N, with a power of 15.8 W kg-1, nearly identical to the mass-specific allometric prediction for the maximum aerobic capacity of other mammals and physiologically possible. The Cd at speeds >2.5 m s-1 indicated reduced turbulence in the boundary layer around the dolphin's body, thereby reducing drag. The ability of dusky dolphins to swim at sustained high speeds resulted from an exponential decrease in Cd, which was further reduced by porpoising, thereby explaining the low drag and locomotory power that resolved Gray's paradox.

Acoustic behaviour in bottlenose dolphins during two different target discrimination tasks

Echolocation is an active sensory system that gives an acoustic representation of the surroundings by the animal emitting clicks, detecting and analysing echoes. However, little is known about dolphin biosonar in moving animals, as well as of the process of controlling click emissions, and the cues used by the animal to discriminate between different targets. We studied how bottlenose dolphins may use their dynamic sound production and hearing abilities, along with head and body movements, to detect and classify objects through echolocation. We designed two different experiments with blindfolded bottlenose dolphins (Tursiups truncatus) swimming freely along the pool and actively discriminating between two targets of three different materials, and a second one to determine the capability to discriminate wall thickness differences in cylindrical targets of the same material. By means of synchronized cameras and hydrophones, we observed clear differences between individuals of the same species in terms of ability to discriminate, but similar performance with the harbor porpoises in relation to the materials chosen with the difficulty of the task. Studying how the dolphins solved a simplified echolocation task, allow a better understanding of the processes behind target detection and discrimination capabilities during natural biosonar circumstances .

Searching in Justification for the Intensification of Upward-Kicking in Dolphin Swimming

Abstract Scientific opinions about the importance of dolphin upward leg movements for swimming performance are still divided. Research on the efficiency of propulsion, similarly generated by a relatively larger the monofin surface, showed that quality of the upward movement phase is a measure of swimming performance. Therefore, the forces generated as a result of upward and downward kicks in butterfly swimming were analysed. The ability of the swimmers to kinaesthetically control of the upward dolphin kicking was also researched. Ten international level butterfly swimmers (mean 18,2±1,4 years) took part in the research. They performed three trials on 25m distance, at maximum speed using the monofin device (The plate of standard monofin was removed and two strain gauges were affixed in the middle, between the toe). They randomly swam: 1) butterfly stroke (BS), 2) dolphin-kicking only (LK) and 3) swam being focused on activation of upward-kicking (AUK). Time dependent signals of the force sagging the fin in reaction to the water resistance were registered. The impulses of force sagging the fin in each stroke were lower in upbeat than in downbeat. The lowest difference was in AUK trial. First, Wilks's test and then Duncan’s post hoc tests for each of the trial showed (at p≤0,05) that: downward impulses for LK was significantly higher than for BS. Upward impulses did not differ between the trials. Downward times for AUK, the same as total trial times, was significantly longer than for BS and for LK Upward times for AUK was significantly longer than for BS. The results demonstrated, that butterfly arms action leads to intensification of both kicking phases. The swimmers were well skilled for kinaesthetic controlling of the dolphin upbeat. They did not obtain the equal proportion between propulsion effect of both kicking phases, but it has been suggested, that this level of skill mastering is out of the human motor abilities. Opportunities for conscious controlling of the efficiency of the upward movement are seen in the modification of the time structure of this phase. These results could be used for improving the leg-kicking performance in butterfly swimming, as well as after stars and turns.

Quantifying the Leaping Motion Using a Self-Propelled Bionic Robotic Dolphin Platform

Kinematic analysis of leaping motions can provide meaningful insights into unraveling the efficient and agile propulsive mechanisms in dolphin swimming. However, undisturbed kinematic examination of live dolphins has been very scarce due to the restriction of close-up biological observation with a motion capture system. The main objective of this study is to quantify the leaping motion of a self-propelled bionic robotic dolphin using a combined numerical and experimental method. More specifically, a dynamic model was established for the hydrodynamic analysis of a changeable submerged portion, and experimental data were then employed to identify hydrodynamic parameters and validate the effectiveness. The effects of wave-making resistance were explored, indicating that there is a varying nonlinear relationship between power and speed at different depths. In addition, the wave-making resistance can be reduced significantly when swimming at a certain depth, which leads to a higher speed and less consumed power. Quantitative estimation of leaping motion is carried out, and the results suggest that with increase of the exiting velocity and angle, the maximum height of the center of mass (CM) increases as well; furthermore, a small exiting angle usually requires a much larger exiting velocity to achieve a complete exiting motion. These findings provide implications for optimizing motion performance, which is an integral part of underwater operations in complex aquatic environments.

Tag-based estimates of bottlenose dolphin swimming behavior and energetics.

Current estimates of marine mammal hydrodynamic forces tend to be made using camera-based kinematic data for a limited number of fluke strokes during a prescribed swimming task. In contrast, biologging tag data yield kinematic measurements from thousands of strokes, enabling new insights into swimming behavior and mechanics. However, there have been limited tag-based estimates of mechanical work and power. In this work, we investigated bottlenose dolphin (Tursiops truncatus) swimming behavior using tag-measured kinematics and a hydrodynamic model to estimate propulsive power, work and cost of transport. Movement data were collected from six animals during prescribed straight-line swimming trials to investigate swimming mechanics over a range of sustained speeds (1.9-6.1 m s-1). Propulsive power ranged from 66 W to 3.8 kW over 282 total trials. During the lap trials, the dolphins swam at depths that mitigated wave drag, reducing overall drag throughout these mid- to high-speed tasks. Data were also collected from four individuals during undirected daytime (08:30-18:00h) swimming to examine how self-selected movement strategies are used to modulate energetic efficiency and effort. Overall, self-selected swimming speeds (individual means ranging from 1.0 to 1.96 m s-1) tended to minimize cost of transport, and were on the lower range of animal-preferred speeds reported in literature. The results indicate that these dolphins moderate propulsive effort and efficiency through a combination of speed and depth regulation. This work provides new insights into dolphin swimming behavior in both prescribed tasks and self-selected swimming, and presents a path forward for continuous estimates of mechanical work and power from wild animals.

PENGARUH FAST INTERVAL TRAINING (FIT) TERHADAP HASIL KECEPATAN RENANG GAYA BEBAS 100 METER PADA ATLET K.U II LUMBA-LUMBA SWIMMING CLUB BINJAI TAHUN 2021

This research was carried out at the Swimming Club Binjai Dolphins at the Tirta Raerim Mencharm swimming pool in the Peacock Meadows, North Sumatra. held on November 10 to January 28, 2021 for 8 weeks with a frequency of 2 times a week.This study aims to determine the effect of fast interval training (FIT) on the results of the 100 meter freestyle swimming speed for the K.U II Dolphin Swimming Club Binjai. The research method used in this study is an experimental method with a sample of 8 people with a purposive sampling research design. Then the sample did an initial test (pre-test), namely with a 100-meter swimming test, then the sample was given Fast Interval Training (FIT) training then after 8 weeks of programmed exercise the sample did a final test (post-test).The results of the analysis of the hypothesis, that there is a significant effect of fast interval training (FIT) training on the results of the 100 meter freestyle swimming speed for the K.U II Dolphin Swimming Club Binjai athletes. 2021 year. The results of the t-test obtained tcount = 0.3096 and t-table = 0.258. At the real level = 0.05 then t-count > t-table. Based on the hypothesis testing criteria, HO is rejected and Ha is accepted. Thus it can be concluded that there is a significant effect of Fast Interval Training (FIT) on the results of the 100 meter freestyle swimming speed for the KU II Lumba-lumba Swimming Club Binjai athletes 2021.

Bubble PIV technique to measure the velocity field of a free-swimming California sea lion

Fish et al. (2014) adapted laboratory PIV for safe use on larger animals. As opposed to seeding the entire flow with reflective particles and illuminating a plane of the flow with a laser, they produced a sheet of small bubbles and used sunlight for global illumination. Underwater cameras imaged the flow in a method similar to traditional PIV. This technique was used to measure the flow around a swimming dolphin and estimate the thrust produced during a tail stand maneuver (Fish et al. (2014, 2018)). In the current work, we will extend the modification of PIV of Fish et al. to measure the flow produced by a swimming sea lion also using bubbles as seeding particles and sunlight as illumination. This is the first time that the flowfield of a swimming sea lion has been directly measured. We will present an extensive extension to the image processing required to measure flow under field conditions. Finally, we will present the flow generated by propulsive strokes of an adult female (Cali) sea lion freely swimming through a pool of stationary water.

Effects of Coastal Construction on Indo-Pacific Humpback Dolphin (Sousa chinensis) Behavior and Habitat-Use Off Hong Kong

Construction-related loss of habitat, degradation of existing habitat, noise pollution, and vessel activity are growing issues for Indo-Pacific humpback dolphins (Sousa chinensis) that occur in the shallow, near-shore, highly industrialized waters off Lantau Island, Hong Kong. We studied the occurrence of dolphins in discrete locations, fine-scale movement patterns, and dolphin behavioral activity states. Potential explanatory variables varied and included year, season, time of day, dolphin group size and behavioral activity state, proximity to construction activity, and vessel type and number. Land-based observations and theodolite tracking of dolphins and vessels were conducted from seven locations to the north of Lantau Island, Hong Kong, and marine construction activities near survey sites were identified. A total of 636 groups of dolphins were recorded, totaling 150.91 h of tracking, from 405 days of observation effort. Hurdle models were used to analyze dolphin occurrence, multivariate generalized additive models were used to analyze fine-scale movement patterns, and log-likelihood ratio and binomialzscorepost hoctests were used to analyze behavioral activity states. Dolphin occurrence was lower in historically important areas near long-term, low-intensity construction activity, and dolphin swimming speed was higher in response to vessel presence. Overall, foraging and traveling were the most frequently observed behavioral activity states and resting behavior was observed off only one location that was not in proximity to construction activities. Temporal overlap in adjacent marine construction areas may displace animals for extended periods and nearby ecologically similar habitats should be identified and designated as marine protected areas to mitigate effects of such disturbance.

‘So long, and thanks for all the fish!’: Urban dolphins as ecofascist fake news during COVID-19

At the time of COVID-19 social distancing, the move from the real to a digital public life has propagated viral videos of ‘capturing’ wild animals performing unusual behaviours in typically urban habitats. From Welsh sheep using roundabouts to dolphins swimming in the Venice canals, the real from the fake becomes difficult to discern through technological advances but also in the belief in the underlying ideological environmental message it enables. In this article, I examine how these viral videos are not only being faked for the social validation of likes and retweets but have also become a tool for ecofascism: a far-right ideology that marries environmentalism with white supremacist ethnonationalism. I examine how social media is used to implicitly spread ecofascist ideas through an environmentalism fakery such as the urban Venetian dolphin that shows how humans, not COVID-19, are the virus and how these human-less vignettes are ultimately used by ecofascists to argue against immigration in order to ‘bring nature back to the natural order of things’. In conclusion, I look at what the initial implications are for communication and environmentalism and the potential these human-less lockdowns have for making convincing arguments for even the smallest of societal changes to mitigate climate change.

Measurement of time-varying kinematics of a dolphin in burst accelerating swimming

Dolphins are well known as excellent swimmers for being capable of efficient cruising and sharp acceleration. While studies of the thrust production and power consumption of dolphin swimming have been the main subject for decades, time-varying acceleration process during successive fluke beats still remains poorly understood. In this study, we quantified the time-varying kinematics of a dolphin (Lagenorhynchus obliquidens) by directly recording its burst-accelerating swimming before vertical jump in an aquarium with two synchronized high-speed video cameras. We tracked the three-dimensional trajectories of its beak, body sides, and fluke. We found that dolphin could quickly accelerate from 5.0 m s-1 to 8.7 m s-1 merely by 5 strokes (i.e. 2.5 fluke beats) in 0.7 seconds. During the strokes, it was further found that the dolphin demonstrated a great acceleration in downstroke but less acceleration or even a slight deceleration in upstroke. Hydrodynamic forces and thrust power for each stroke were further estimated based on the equation of body motion and a static hydrodynamic model. The drag coefficient of the dolphin was estimated through computational fluid dynamics (CFD) modeling of the steady flows around a realistic geometric model based on 3-D scan data. The thrust and thrust power were then calculated by combining the body kinematics and the drag coefficient, resulting in a maximum stroke-averaged thrust and power-to-mass ratio of 1.3 × 103 N and 90 W kg-1 at downstroke, and 3.3 × 102 N and 19 W kg-1 at upstroke, respectively. Our results point out the importance of asymmetric kinematics in burst acceleration of dolphin, which may be a useful mechanism for biomimetic design of high-performance underwater robots.

Effects of tail fin kinematics on propulsive performance in dolphin swimming

Effects of tail fin kinematics on propulsive performance in dolphin swimming

Postcards

Postcards Barbara Lehman This fictionalized biography tells the story of James Caste an autistic, deaf, completely self-taught American artist, born in Idaho in 1899. The art he produced, his silent interpretation of the world, made sense of his rural setting through drawings of houses, furniture, symbols, and people. Many of them were produced with homemade materials such as sticks dipped into soot and saliva, then applied to scraps of paper. As an artist and a human being, Castle was sadly misunderstood, but at middle age, his startlingly childlike yet innovative art was discovered and given attention. Castle's boyhood and life are beautifully—and painfully—depicted in watercolors, pencil, and some of the same primitive tools used by Castle. Say's three final portraits of Castle are simple and sensitive. The book raises an important question: How many children today—special needs or not—also find solace and meaning in their art? Patricia Bloem Allen Say Silent Days, Silent Dreams New York: Arthur Levine Books, 2017. 64 pp. ISBN: 987-0-545092761-1 (Nonfiction; ages 10+) [End Page iv] Potiki, who loves to sing, is the youngest brother of three. The eldest, Tahi, is good at working the land, and Rua, the second brother, has fishing skills They never want Potiki to accompany them on hunting and fishing trips because his singing disturbs them. One day Potiki hides under the canoe nets, but they find him and throw him into the sea. When their grandmother asks Tahi and Rua about Potiki they deny any knowledge. However, the whales tell the grandmother of a new dolphin swimming in the region and she knows the brothers were lying. As punishment, she turns them into rocks in the Pathway of the Whales. The peritext states that occasionally on the east coast of the North Island of New Zealand, a dolphin plays with people in the sea. The story, in both Māori and English, is accompanied by beautiful ink and watercolor illustrations. Nicola Daly Mere Whaanga The Singing Dolphin / Te Aihe i Waiata Auckland: Scholastic, 2017. 32 pp. ISBN: 9781775434023 (Picturebook; ages 4–7) [End Page 13] When the kingfisher tries to catch a giant fish that is bigger than a fox and looks like a cloud in the sky, the antelope accompanies the kingfisher on its journey in this story about the importance of supporting friends. On the last page, the kingfisher triumphantly holds the giant fish in its mouth on top of the mountain and appears to be on top of the world as his dream comes true. The animals expressions and movements are subtle but deliver their feelings to readers well. The entire story is illustrated in double-spread pages with vivid colors in bright tones. Young readers will be surprised to know that the author worked as a zookeeper for twenty-five years, and they will learn that the illustrations are based on his knowledge and observations of animals at the zoo. This self-taught artist is an award winner in Japan. Jongsun Wee Hiroshi Abe 雲をつかむはなし [A Story of Grabbing Clouds] Tokyo: Media Pal, 2017. 32 pp. ISBN: 9784802130486 (Picturebook; ages 4+) [End Page 25] A class of children on a day trip in a safari park with a missing hippopotamus provides the setting for this rhyming romp. As the class arrives at the park, one child observes there is no hippopotamus listed at the gate. The park owner assures them there is a hippopotamus, but when they go to look at the lake, its not there. Thus starts the hunt by the children, many of whom patently don't know what a hippopotamus looks like. The rhyming texts perfect meter comes back with balanced regularity to the class refrain, That's not a hippopotamus!" Detailed, humorous illustrations allow young viewers to spot the hippopotamus on the illustrations' periphery, while everyone in the class except for young Liam misses it. This was a well-deserved winner of the 2017 Best Picturebook Award from the New Zealand Book Awards for Children and Young Adults. Nicola Daly Juliette MacIver That's Not a Hippopotamus! Illus. Sarah Davis Wellington: Gecko Press, 2016. 30 pp. ISBN: 9781927271971 (Picturebook; ages 2–7) [End...

Evaluation of Dolphin Swimming Speed and Thrust Based on CFD

Evaluation of Dolphin Swimming Speed and Thrust Based on CFD

Experimental Measurement of Dolphin Thrust Generated during a Tail Stand Using DPIV

Estimation of force generated by dolphins has long been debated. The problem was that indirect estimates of force production for dolphins resulted in low values that could not be validated. Bubble digital particle image velocimetry (DPIV) measured hydrodynamic force production for swimming dolphins and demonstrated high force production. To validate the bubble DPIV and reconcile force production measurements, two bottlenose dolphins (Tursiops truncatus) performing tail stands were measured with bubble DPIV. Microbubbles were generated from a finely porous hose and compressed air source. Displacement of the bubbles by the propulsive motions of the dolphin was tracked with a high-speed video camera. Oscillations of the dolphin flukes generated strong vortices and a downward directed jet flow into the wake. Application of the Kutta–Joukowski theorem measuring vortex circulations yielded forces up to 997.3 N. Another video camera recorded body height above the water surface to determine the mass-force of the dolphin above the water surface. For the dolphin to hold its position above the water surface, the mass-force approximately balanced the vertical hydrodynamic force from the flukes. The results demonstrated the fluke motions generate high sustained forces roughly equal to the dolphin’s weight out of the water. Bubble DPIV validated high forces measured previously for thrust generated in swimming by animals and demonstrated a more accurate technique compared to standard aerodynamic analysis.

Avoiding Being a Crushed Prawn and Becoming a Dolphin Swimming between the Two Fighting Whales? South Korea’s Strategic Choice in the Face of the Intensifying Sino–US Competition

This article presents an analysis of South Korea’s strategic choices over the Asian Infrastructure Investment Bank (AIIB), the Trans-Pacific Partnership (TPP), and the Terminal High Altitude Area Defense (THAAD) in light of the Sino–US competition in post-Cold War East Asia. South Korea’s puzzling behavior here represents Seoul’s hedging strategy against the uncertain future of the Sino–US competition in East Asia. The driving force of South Korea’s hedging behavior is Seoul’s dual concerns about being excessively dependent on the USA for its security at the time of China’s rapid rise on the one hand and being pulled into a growing China’s sphere of influence at the expense of traditional US–ROK security ties on the other. Reflecting Seoul’s prudent balancing acts between the two superpowers, South Korea’s hedging often results in apparently indecisive and underdetermined strategic choices in the face of the intensifying Sino–US competition. Nevertheless, South Korea’s hedging strategy allows Seoul to deepen extensive economic ties with Beijing while maintaining a traditional security alliance with Washington. The hedging behavior of South Korea, which is uniquely positioned as a strategic partner of rapidly rising China as well as a key security ally of the rebalancing USA, sheds important light on the behavior of middle powers in alliance politics, which has largely been neglected in the current literature.

Sleeping on the wing.

Wakefulness enables animals to interface adaptively with the environment. Paradoxically, in insects to humans, the efficacy of wakefulness depends on daily sleep, a mysterious, usually quiescent state of reduced environmental awareness. However, several birds fly non-stop for days, weeks or months without landing, questioning whether and how they sleep. It is commonly assumed that such birds sleep with one cerebral hemisphere at a time (i.e. unihemispherically) and with only the corresponding eye closed, as observed in swimming dolphins. However, the discovery that birds on land can perform adaptively despite sleeping very little raised the possibility that birds forgo sleep during long flights. In the first study to measure the brain state of birds during long flights, great frigatebirds (Fregata minor) slept, but only during soaring and gliding flight. Although sleep was more unihemispheric in flight than on land, sleep also occurred with both brain hemispheres, indicating that having at least one hemisphere awake is not required to maintain the aerodynamic control of flight. Nonetheless, soaring frigatebirds appeared to use unihemispheric sleep to watch where they were going while circling in rising air currents. Despite being able to engage in all types of sleep in flight, the birds only slept for 0.7 h d-1 during flights lasting up to 10 days. By contrast, once back on land they slept 12.8 h d-1. This suggests that the ecological demands for attention usually exceeded that afforded by sleeping unihemispherically. The ability to interface adaptively with the environment despite sleeping very little challenges commonly held views regarding sleep, and therefore serves as a powerful system for examining the functions of sleep and the consequences of its loss.

尾ヒレと胴体の振動によるイルカ遊泳の計算流体力学モデリングと推力発生メカニズムの研究

尾ヒレと胴体の振動によるイルカ遊泳の計算流体力学モデリングと推力発生メカニズムの研究

Watch a dolphin swim with a first-of-its-kind artificial fluke

Watch a dolphin swim with a first-of-its-kind artificial fluke

Bottlenose Dolphin Hydrodynamics Research

Data collected thus far, including surface photography, and underwater high definition video footage, have provided answers to many initial questions while providing opportunities for further studies, such as, dolphin burst speeds used in catching fast swimming fish and/or avoiding predatory attacks. It’s not until looking at images frame by frame, that we see what wonderful examples of natural design dolphins truly are. The information and photographs provided in this article were taken from lecture notes, surface and underwater photography, and isolated video sequence imagery obtained utilizing open ocean trained dolphins. Numerous websites state average dolphin swimming speed ranges between: 3 7 and 7 8mph. My research findings are provided below.