In this thesis, we investigate mixing and transport mechanisms within complex flows, with a particular interest on stretching. Stretching, driven by localized deformation within the fluid domain, provides insight into the underlying dynamics that drive the formation of coherent structures across a wide range of spatial scales. By measuring particle separation rates, we can quantify the extent of deformation in the fluid. Regions that experience significant stretching reveal coherent structures that remain stable over finite time intervals. Understanding how stretching operates within fluid domains is essential for comprehending the flow dynamics of both experimental and simulated systems. To investigate these mechanisms, we introduce a novel high-speed imaging technique to directly capture the fluid dynamics of complex flows. Additionally, we develop robust computational methods to analyze and process the inherently noisy data, enabling accurate insights into the deformation and structure formation in the fluid domain. Finally, we demonstrate the application of our high-speed imaging system and computational tools by studying a bio-inspired system, the flows generated by a pulsing soft robotic coral.