Heat shock protein 70s (Hsp70s) are a highly conserved class of molecular chaperones that are involved in cellular processes in all organisms such as stress response, homeostatic maintenance, and cell cycle progression. The organism Nematostella vectensis, or the starlet sea anemone, experiences a multitude of physiological stressors through abiotic factors such as temperature, UV radiation, salinity, and pollutants like toxic metals. Due to the dynamic estuary environments that N. vectensis resides, these stressors are experienced with both daily and seasonal fluctuations. In marine cnidarians, Hsp70 proteins can be effective biomarkers in order to determine adaptations and evolutionary responses to environmental stress: a pressing issue as concerns about climate changes grow. Within N. vectensis, 3 isoforms of cytosolic Hsp70 (NvHsp70) exist: A, B, and D. Transcriptional data has shown dramatic differences among expression profiles of these NvHsp70 isoforms under stress. To bypass the lack of in vivo protein technologies available for marine invertebrates, the 3 NvHsp70 isoforms were expressed in Saccharomyces cerevisiae budding yeast lacking native Hsp70. These cells grow at different rates and display altered tolerance to stressors such as heat shock, DNA damage, and salinity. After functional differences at the organismal level were investigated, each isoform and their respective complex of bound proteins ("interactomes") were characterized using mass spectrometry. From these characterizations, differences in binding behaviors were observed. Each isoform expressed a unique interactome upon heat stress, and bound to different co-chaperones. Of the 3 isoforms, NvHsp70B showed a substantially large number of increased interactions in response to heat shock as compared to NvHsp70A and NvHsp70D. Using the data gathered throughout the course of this thesis, each of the NvHsp70 isoforms’ roles were further characterized.