Date of Award

Spring 2018

Document Type

Thesis Restricted

Degree Name

Master of Science (MS)

Department

Biology

Committee Chairperson

Frank Fish, Ph.D.

Committee Member

Jennifer Maresh, Ph.D.

Committee Member

Josh Auld, Ph.D.

Abstract

Dorso-ventral oscillations of cetacean caudal flukes generate lift-based thrust that allows them to operate with a high propulsive efficiency. Flexibility of the tail flukes is an important element in this system and the ability to rotate the flukes about the ball vertebra allows for changes in angle of attack and smooth bending. There are three sets of tendons that pass through the odontocete peduncle and insert onto the caudal vertebrae. It is unknown to what extent these tendons effect fluke flexibility. The purpose of this study was to investigate direct effects of peduncle tendons on odontocete fluke flexibility, deflection angle and investigate tendon elasticity. A one-point bending test was conducted on an isolated fluke that was immobilized at its base. Tension was created by the addition of weight to each tendon. Tensile testing was performed on tendons using an Instron 5848 MicroTester. Histological analyses of collagen fibers were done on tendons at the New Bolton Center (UPenn). Flexibility of the fluke decreased and deflection angle increased as a result of tension applied to tendons indicating the possibility that these tendons play a role in fluke thrust production. Young’s modulus differed among tendons in the peduncle and was overall more compliant than average mammalian tendons. The collagen fibers that make up the three sets of tendons in the cetacean peduncle were found to be longitudinally wavy, suggesting the ability to store elastic energy. These results indicated that there is an element of active control of flexibility in odontocete flukes during locomotion.

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