1. The Effects of Tail Flukes on the Swimming Pattern of Atlantic Bottlenose Dolphins Lauri Leach Senior Honors Project Faculty Sponsor: Dr. Cheryl Wilga Biological Sciences

2. Background (Fish 2009) Dorsal Fin Tail Flukes Peduncle Pectoral Fin Rostrum Blowhole Dolphin Anatomy Species Atlantic Bottlenose Dolphin Tursiops truncatus

3. Introduction Atlantic bottlenose dolphins are top predators in the wild, in part because they are excellent swimmers. Their swimming pattern is described as a carangiform mode with semilunate tail, which is shared by other fast swimming vertebrates with a similar body type, such as the great white shark and the tuna (Fish & Hui, 1991). However, contrary to fish, marine mammal tails insert differently on the body with the foil oriented in a coronal plane (Fish 1993). When dolphins swim through the water, the tail flukes act as a hydrofoil as they move dorsoventrally, generating thrust to propel the animal through the water (Fish, 1993). Thrust is created in both the up- stroke and the down-stroke of the tail, but the magnitude of thrust during each stroke may vary (Fish & Hui, 1991). Dolphins use the pectoral fins and dorsal fin for maneuverability and stability as they swim (Fish & Hui, 1991). Using this style of swimming, Atlantic bottlenose dolphins can swim up to 25 miles per hour and leap 15 to 20 feet into the air. A dolphin without tail flukes cannot swim in this manner and must adapt to a different style of swimming. The only known dolphin with this condition lost its tail flukes, the joint connecting the flukes to the tailstock, and three adjacent vertebrae as the result of becoming entangled in a crab trap.

4. Questions How do tail flukes affect the swimming pattern of Atlantic bottlenose dolphins? How does swimming with (1) an intact tail, (2) damaged tail or (3) without tail flukes differ? How does a prosthetic tail change the swimming pattern of a dolphin without tail flukes?

5. Significance Little is known about the swimming pattern of dolphins without tail flukes because there is only one known dolphin in the world that has survived with this condition. Swimming in unnatural ways can harm the body and affect the long-term health of an animal. The only known dolphin without tail flukes is facing spinal injury and scoliosis in the future as a result of her swimming pattern. Studies like this will help to develop animal prosthetics and might have applications to human health. The final version of the prosthetic tail isn’t finished yet, but new knowledge gained from working on it has already been applied to human prosthetics.

6. Materials and Methods Using an 8mm Sony Digital Handycam, I filmed three resident dolphins at the Clearwater Marine Aquarium in Clearwater, Florida. One of the dolphins has intact tail flukes, one has damaged tail flukes, and one has missing tail flukes. I filmed underwater sequences from lateral and anterior points of view through underwater viewing windows. In addition, video was obtained from dorsal points of view from the roof directly above the dolphin pool. The dolphins were filmed outside of training sessions while they leisurely swam around the pool. I also obtained a copy of underwater video footage from a lateral point of view of the dolphin without tail flukes using a prosthetic tail during a training session. After sorting through my sequences, I was able to find five lateral sequences of each dolphin. I had seven lateral sequences of the dolphin wearing the prosthetic tail. I had six dorsal sequences of the dolphins with intact and damaged tail flukes and six anterior sequences of the dolphin with missing tail flukes. Since I was unable to obtain dorsal views of the dolphin without tail flukes, I used anterior sequences because both anterior and dorsal views will show side-to-side movement that can be scaled to the animal size. Intact FlukesDamaged FlukesMissing Flukes

7. Once I found the sequences I wanted to use, the sequences were broken down into individual frames using the program Matrox PC-VCR. Next, I digitized points on the animal that related to body, tail, and pectoral fin movement using Didge Image Digitizing Software. Using the digitized points, I was able to measure several aspects relating to each dolphin’s swimming pattern. In the lateral sequences, I measured rostrum – pectoral fin angle, dorsal tip – tail fluke angle, whole body angle, vertical movement and velocity of the peduncle, vertical movement and velocity of the rostrum, and anterior movement and velocity of the rostrum. From dorsal and anterior views I measured rostrum-pectoral fin angle, whole body angle, lateral movement and velocity of the peduncle, and lateral movement and velocity of the rostrum. I measured anterior movement and velocity of the rostrum in the dorsal sequences as well. All distance measurements were divided by the length from the rostrum to the base of the pectoral fin of each dolphin in order to make the distances and velocities relative to the size of the animal. The data was analyzed using SigmaStat 3.11. One-Way ANOVA tests were used on indexed data. When Normality or Equal Variance tests failed, a Tukey test or a Kruskal-Wallis One Way Analysis of Variance on Ranks was performed. A calculated p value of less than 0.05 was considered statistically significant. Materials and Methods

8. Methods β Pectoral Fin Angle γ β α α Dorsal fin to Flukes Angle Whole Body Angle α β Lateral Dorsal Anterior http://www.wildernessclassroom.com/hsmb/i mages/library/bottlenose_dolphin.jpg (Fish 2009)

9. Results Intact Tail Flukes – Lateral View

10. Results Intact Tail Flukes – Dorsal View

11. Results Damaged Tail Flukes – Lateral View

12. Results Damaged Tail Flukes – Dorsal View

13. Results Missing Tail Flukes – Lateral View

14. Results Missing Tail Flukes – Anterior View

15. Results Missing Flukes with Prosthetic Tail– Lateral View Filming Credit to Joe Malo and CMA

16. Results There was very little pectoral fin movement in the swimming patterns of the dolphins with intact and damaged tail flukes. In contrast, there was a lot of pectoral fin movement in the dolphin with missing tail flukes. The mean rostrum-pectoral fin angle between a dolphin with intact tail flukes and one with missing tail flukes was also significantly different. The angle in intact dolphins did not vary much, while the angle in the dolphin with missing tail flukes fluctuates greatly around the mean value, which was much lower than the mean value seen in intact dolphin swimming.

17. Rostrum – Pectoral Fin Angle Intact DorsalMissing Anterior Missing LateralIntact Lateral Angle (degrees) Time (ms) P = 0.003 Mean = 55°Mean = 25° Mean = 175° Mean = 146°Mean = 164° Mean = 109°

18. Results In the dorsal and anterior views, dolphins with intact and missing tail flukes exhibit statistically significant differences in whole body angle. The dolphin with the intact tail seemed to move straight across the screen with little side-to-side movement, i.e. yaw. This can be seen in the data because the whole body angle barely changed as the dolphin swam. The angle fluctuated slightly around the mean. The dolphin without tail flukes exhibited significant changes in whole body angle. It also demonstrated a lower mean value, as well as a much higher change in angle during the length of each sequence. This means that unlike the intact dolphin, the dolphin with missing flukes is curving its body side to side. The dorsal tip to fluke tip angle was also significantly different when the intact dolphin was compared to the dolphin with missing tail flukes. Although the changes in the angles themselves were not significantly different, the mean angles were. The dolphin with missing tail flukes consistently exhibited a much smaller dorsal tip to fluke tip angle than the intact dolphin.

19. Whole Body Lateral Angle Intact DorsalMissing Anterior Missing LateralIntact Lateral Angle (degrees) Time (ms) P = 0.003 Mean = 164°Mean = 94° Dorsal Tip - Fluke Angle Mean = 116°Mean = 177° P = 0.002

20. Results When comparing the swimming pattern of a dolphin with intact or damaged tail flukes to a dolphin with missing tail flukes, the lateral movement of the rostrum was significantly different. The intact dolphin didn’t show much side-to-side movement of the rostrum in the video, and the data shows very little change in distance over time. In the anterior view of the dolphin with missing tail flukes, the rostrum moves a significant amount in relation to a background point. As the body of the dolphin curves side to side, its rostrum exhibits a side-to- side motion as well. The anterior, or forward movement, of the rostrum was also significantly different between these groups. All three dolphins were moving forward, but the dolphin with missing tail flukes was not covering as much distance in the same amount of time.

21. Rostrum vs. Background Intact DorsalMissing Anterior Lateral Distance (cm) P = 0.003 Total = 0.35cmTotal = 2.26cm Time (ms) (Fish 2009) http://www.wildernessclassroom.com/hsmb/i mages/library/bottlenose_dolphin.jpg

22. Rostrum vs. Background Missing LateralIntact Lateral Time (ms) P < 0.001 Total = 1.73cm Anterior Distance (cm) Total = 2.73cm (Fish 2009)

23. Results A significant difference was also found when comparing the lateral peduncle movement and velocity of the intact and damaged dolphins to the one without tail flukes. The intact and damaged dolphins didn’t show much side-to-side movement of the peduncle as they swam. The data shows very little change in lateral peduncle movement over time. The dolphin without a tail had much more peduncle movement. As the whole body moved side-to-side, the peduncle followed this pattern, resulting in a significantly higher total amount of movement (distance). The velocity of the lateral peduncle movement was also significantly different. The dolphin without tail flukes showed more drastic changes in velocity, and it also had a higher mean, max, and total velocity. The velocity of the peduncle was calculated for each frame by comparing it to the previous frame. Mean velocity, therefore, was the average of all the individual velocities. The max velocity was the highest of these values. Total velocity was calculated by taking the total distance moved over total time.

24. Peduncle vs. Background Intact DorsalMissing Anterior Distance (cm) P = 0.005 Total = 0.281cmTotal = 4.56cm Time (ms) (Fish 2009)

25. Peduncle vs. Background Missing AnteriorIntact Dorsal Time (ms) P < 0.001 Max = 0.0102cm/ms Total = 0.0009cm/ms Velocity (cm/ms) Max = 0.0016cm/ms Total = 0.0004cm/ms (Fish 2009) http://www.wildernessclassroom.com/hsmb/i mages/library/bottlenose_dolphin.jpg

26. Results While there were several variables that were significantly different between the intact dolphin and the dolphin with missing tail flukes, the swimming pattern of a dolphin with damaged tail flukes was not significantly different from the pattern of a dolphin with fully intact flukes. None of the variables that were measured exhibited a significant difference between the intact and damaged dolphins. There were also no statistically significant differences between the dolphin wearing the prosthetic tail and the swimming patterns of the dolphins with intact, damaged, and missing tail flukes. The mean fluke angle of the dolphin swimming with the prosthetic tail was not significantly different from the angles found in intact and missing tail fluke swimming. In the lateral view, the pectoral fin angle of the dolphin with the prosthetic tail was not significantly different than the angles found in damaged and missing tail fluke swimming. Since the swimming pattern with the prosthetic tail was not significantly different from intact or missing tail fluke swimming, but dolphins with intact and missing tail flukes are significantly different from each other, it is clear that something about the prosthetic tail swimming is not normal.

27. Discussion Tail flukes provide most of the propulsion dolphins use when swimming. Swimming with intact and damaged tail flukes are not significantly different, however swimming without tail flukes is significantly impaired. The dolphin in this study has adapted to swim in a side-to-side motion, rather than in the up-and-down motion of a normal dolphin. The significantly increased motion of the pectoral fins in the dolphin without tail flukes could be an effort to create propulsion by paddling in order to partly make up for what was lost with the tail flukes. This significantly increases lateral movement of the peduncle and rostrum. Increased yaw creates more drag, which results in the dolphin without tail flukes being less efficient and not as fast as a normal dolphin. This will also result in the use of more energy to swim. Higher lateral velocity of the peduncle and more drastic changes in velocity are then needed to overcome drag and create forward motion. After several training sessions, the dolphin with the prosthetic tail was able to move in an up-and-down motion, although it is unknown whether it does so in the same way as a normal dolphin. It is impossible to tell from this data whether the swimming pattern seen with the prosthetic tail is something in between the missing and intact patterns or if the dolphin varies between a missing and intact pattern of swimming while wearing the tail because it is still learning the behavior of moving up-and-down.

28. Discussion Flexibility of the tailstock in dolphin fetuses, neonates, and juveniles was studied recently. It was discovered that dolphin fetuses are bent ventrolaterally in the uterus, and as a result, newborn dolphins have a higher degree of lateral flexibility than adults (Etnier, et al., 2008). Since neonates must be able to swim dorsoventrally to get to the surface and breathe, they need some way to control and prevent lateral movements. Mechanical changes begin to produce structural stiffness of the tailstock when a dolphin is around three weeks of age (Etnier, et al., 2008). Previous research showed that newborn dolphins use muscles to actively prevent lateral movement of the tailstock. It was shown that as a dolphin grows, structural stiffness of the tailstock increases and overall body curvature decreases as body length increases (Etnier, et al., 2008). It is possible that the dolphin without tail flukes in this study maintained some of the lateral flexibility seen in neonates and juveniles when it lost its tail flukes since this incident occurred when the dolphin was only two months old. Perhaps the dolphin was able to adapt and survive with this condition because the loss of tail flukes occurred at such a young age. If this had happened to an older dolphin, it is possible that adaptation would not have been possible because the structural stiffness of the tailstock would have prevented the side-to-side motion required for swimming without tail flukes.

29. Future Suggestions Most significant differences were detected in anterior and dorsal views, so footage of the prosthetic tail in one of these views could reveal important information. Only three dolphins were used and only five or six sequences were analyzed in each view, so the statistical analyses are not as robust as desired. More data may fix this problem.

30. Implications The dolphin in this study lost its tail flukes, the joint that connects the flukes to the tailstock, and three adjacent vertebrae as a result of becoming entangled in a crab trap. Entanglement and entrapment are always a possibility whenever there is fishing gear left in the water where marine mammals are present. It has been estimated that over 300,000 cetaceans worldwide die every year after becoming entangled in fishing gear (NOAA). The number of marine mammals that get entangled is much higher, due to the fact that some animals are disentangled, while others strand, are rescued, rehabilitated, and released back into the wild. In Alaska during the year of 2006, 20 of the 117 reported animal strandings were due to entanglement (Lowe & Sternfeld, 2007). This study shows how only one entanglement changed one animal’s style of swimming and essentially her whole way of life. This dolphin can no longer survive in the wild as a result of the loss of its tail flukes. Even though this is one of many similar stories, it shows just how important it is to keep the oceans clean in order to protect the animals that live in them so that situations like this one can be prevented in the future.

31. Works Cited 1.) Etnier, S.A., McLellan, W.A., Blum, J., & Pabst, D.A. 2008. Ontogenetic changes in the structural stiffness of the tailstock of bottlenose dolphins (Tursiops truncatus). The Journal of Experimental Biology 211: 3205-3213. 2.) Fish, Frank. 1993. Power output and propulsive efficiency of swimming bottlenose dolphins (Tursiops truncatus). The Journal of Experimental Biology 185: 179-193. 3.) Fish, F. & Hui, C. 1991. Dolphin swimming – a review. Mammal Review 21(4): 181-195. 4.) Lowe, C. & M. Sternfeld. 2007. Draft 2007 Alaska Region Marine Mammal Stranding Summary. National Marine Fisheries Service, February 6, 2007. 5.) Marine Mammal Entanglement: Large Whale Entanglements. NOAA Fisheries: Alaska Regional Office. http://www.fakr.noaa.gov/protectedresources/entanglement.htm. http://www.fakr.noaa.gov/protectedresources/entanglement.htm

32. Acknowledgements Special thanks to Dr. Cheryl Wilga for sponsoring my project and for helping me every step of the way. Also thanks to: *Abby Stone and Elaina Franklin for letting me behind the scenes and for gating the dolphins so that I could film them. *Joe Malo for helping me figure out how to get underwater footage and for providing me with his footage of the underwater prosthetic tail session. *The Clearwater Marine Aquarium for allowing me to film their dolphins. *Anabela Maia for helping me in the lab, reviewing my final product, and for being supportive and interested in my project. *Mr. Swindon for awarding me with the Joan Irvine Smith and Athalie R. Clark Award for Environmental Research to help cover costs for my project. *My parents for helping to pay for me to fly down to Florida so I could film.