Despite there being some evidence that jellyfish may actively affect their position, the role of active swimming in controlling jellyfish movement and the characteristics of jellyfish swimming behavior, have not been fully understood. As a result, jellyfish are often considered as passively drifting or randomly moving organisms. But a recent study using drone videos helped understand and track multiple adjacent jellyfish. The maximum depth of the jellyfish observed in the drone footage was less than 4 metres. The video analysis showed that the movement of jellyfish is modulated by distinctly directional swimming patterns that are oriented away from the coast and against the direction of surface gravity waves. The behaviour of individual jellyfish translates into a synchronised directional swimming of the aggregation as a whole. The study showed the importance of active swimming in regulating jellyfish movement. The researchers undertook numerical simulations, which showed that the counter-wave swimming behavior of jellyfish results in biased correlated random-walk movement patterns that reduce the risk of stranding. This provides the jellyfish with an adaptive advantage critical to their survival.
