.................................................................................................................................. ii Acknowledgments................................................................................................................... iv List of Tables ......................................................................................................................... vii List of Figures....................................................................................................................... viii List of Abbreviations ............................................................................................................... x I. Coral bleaching: Acellular breakdown in symbiosis .............................................................. 1 II. Histological and ultrastructural analysis of cell types within the tentacle tissues of the symbiotic anemone, Aiptasia pallida.......................................................................................19 Abstract ........................................................................................................................19 Introduction ..................................................................................................................20 Materials and Methods .................................................................................................22 Results and Discussion .................................................................................................24 Conclusions ..................................................................................................................51 III. Host autophagic degradation and associated symbiont loss occur in response to heat stress in the symbiotic anemone, Aiptasia pallida .................................................................................54 Abstract ........................................................................................................................54 Introduction ..................................................................................................................55 Materials and Methods .................................................................................................58 Results and Discussion .................................................................................................63 Conclusions ..................................................................................................................73