.................................................................................................................................. ii Acknowledgments .................................................................................................................... v List of Tables ......................................................................................................................... vii List of Figures ....................................................................................................................... viii List of Abbreviations................................................................................................................ x I. A review of Symbiodinium symbioses with an emphasis on initiation and maintenance of the Cnidaria-Symbiodinium association ...................................................................................... 1 II. Immunohistochemical variation amongst Symbiodinium isolates .................................... 35 III. Ultrastructural variation amongst Symbiodinium isolates ................................................ 57 III. Ultrastructural and biochemical variation amongst Symbiodinium isolates demonstrates variation in storage molecules .......................................................................................... 84 References ..........................................................................................................................105