Dynamic metachronal ciliary patterns enable complex microswimming behavior

Cilia are ubiquitous slender cellular appendages usually found in dense arrays beating in coordinated patterns to generate fluid flow vital for a wide range of biological functions, such as the propulsion of microscopic organisms. A common temporal ciliary pattern is metachronal waves, formed as neighboring cilia beat with small phase shifts. Despite their prevalence, the role of metachronal waves in driving diverse complex motion remains poorly understood. To address this gap, we investigate how metachronal ciliary patterns drive the swimming behavior of a unicellular predator, Didinium nasutum, by combining macroscopic cell tracking with high spatiotemporal imaging. We detect complex swimming trajectories that emerge from continuous transitions between discrete modes of motion and identify the discrete metachronal patterns that enable each swimming state. In addition, we observe that transitions between states require rapid loss of coordination, followed by ciliary pattern rearrangements. To further understand the impact of these changes, we incorporate experimental data into a minimal computational model, revealing their role in modulating propulsion and maneuverability. This work enhances our understanding of how dynamic cilia coordination supports complex swimming behavior, offering new insights into locomotion strategies in unicellular organisms.