Title

The Effects of Tail Flukes on the Swimming Pattern of Atlantic Bottlenose Dolphins

Author(s)

Lauri Leach, University of Rhode IslandFollow

Advisor

Wilga, Cheryl [faculty advisor, Department of Biological Sciences]

Date

5-2009

Keywords

dolphins; swimming; tail flukes; marine mammal; animal prosthetics

Abstract

Atlantic bottlenose dolphins are top predators in the wild, due in part because they are excellent swimmers. When dolphins swim through the water, the tail flukes are moved in an up and down motion to propel the animal through the water. They use the pectoral fins for steering and braking, and the dorsal fin for stabilization as they swim. 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.

During the spring of 2008, I was an intern at the Clearwater Marine Aquarium in Florida. The aquarium is home to a unique Atlantic bottlenose dolphin named Winter. Winter is the only dolphin in the world in captivity that has survived without a tail. Not only is Winter missing her flukes, but she is also missing the joint that connects the tail to the tail stalk and three adjacent vertebrae. Winter has learned to swim using lateral undulation (side-to-side motion), similar to a shark or a fish, instead of using the normal vertical undulation (up-and-down) motion of intact dolphins.

For my honors project, I am analyzing and comparing the swimming patterns of three dolphins with various tail conditions: one with intact tail flukes, one that lacks all of the flukes and part of the tail (Winter), and one that is missing only part of the tail flukes. I will quantify swimming movements of the body, tail and pectoral fins to detect at what point deviations, if any, are made to the normal swimming pattern.

In order to determine what changes Winter has made to learn how to swim with no tail flukes, I filmed several sequences of the three dolphins swimming underwater from lateral, head-on and dorsal viewpoints. I then saved these sequences as individual frames and digitized several points on the animal related to tail and pectoral fin movement.

There is a distinct difference between the swimming pattern of Winter and the other two dolphins. Winter’s side-to-side movements can be seen along the entire body from lateral and head-on views while the intact dolphin and the dolphin with partial tail flukes swim in a normal up-and-down movement with no side to side motion. Winter also swims much slower than the others due to the lack of strong propulsion that flukes would normally provide, regardless of lateral or vertical undulatory movements.

The trainers at the Clearwater Marine Aquarium are working with Hangar Orthopedics to develop a prosthetic tail for Winter. They are experimenting with different materials and forms of the tail, and are teaching Winter how to use and wear the prosthetic. Since she lost her tail at a very young age, she has forgotten how to swim using the vertical undulation of a normal dolphin, so she is currently relearning how to do this. For the final part of my project I am analyzing Winter’s swimming pattern with the prosthetic and comparing it to swimming style of the intact dolphins. This will show how her swimming pattern changes as she adjusts to having a prosthetic tail. I hope to be able to help the trainers figure out how to train Winter, and other dolphins lacking tails, to swim in the most natural way possible.