A groundbreaking study from the Leon H. Charney School of Marine Sciences at the University of Haifa has revealed that Rhopilema nomadica, the most common jellyfish in the southeastern Mediterranean, can actively direct their movements against the flow of water. Published in the esteemed journal Current Biology, this research overturns long-held assumptions about jellyfish behavior, suggesting that these ancient creatures are far more navigationally adept than previously believed.

Jellyfish: More Than Drifters in the Sea

Until now, it was widely assumed that jellyfish aggregations drift aimlessly, their movements dictated solely by ocean currents. However, this new study reveals that jellyfish along Israel's coastline swim purposefully westward, directly against the direction of incoming waves. “We’ve always thought of jellyfish as passive drifters, but our research shows that they possess a significant degree of control over their movements,” said Dr. Yoav Lehahn, lead researcher from the Department of Marine Geosciences at the University of Haifa.

Exciting news! Our project on jellyfish swimming has been published. Led by Dror Malul, Yoav Lehahn, and @UriShavit, with great collaboration from Tel Aviv University, Hebrew University, Technion and University of Haifa. Check out our findings! https://t.co/xM6K4wq1DX#jellyfish pic.twitter.com/O7kJy8y5nG

— Tamar lotan (@tamar_lotan) August 6, 2024

Jellyfish, belonging to the ancient phylum Cnidaria, have existed for over 500 million years without any major changes to their morphology. Despite their long history, much about their behavior, particularly their movement patterns, remains shrouded in mystery. Understanding these patterns is not just a matter of scientific curiosity; it’s crucial for predicting jellyfish invasions that can disrupt human activities, particularly at coastal facilities such as power stations and desalination plants.

A Collaborative Effort to Unveil the Mysteries of Jellyfish Movement

In a coordinated effort involving researchers from the Technion, the Hebrew University of Jerusalem, and Tel Aviv University, Dr. Lehahn's team embarked on an ambitious project to map and analyze the swimming behaviors of jellyfish aggregations along Israel’s coast. The researchers employed a suite of innovative methods to gather data, beginning with aerial surveillance. A light aircraft scouted the coastline from Ashkelon to Nahariya, mapping jellyfish clusters and identifying the most significant aggregations.

Next, drones launched from research boats hovered over these jellyfish groups, capturing high-resolution images and videos that documented their movements. The researchers then compared these observations with data on sea currents and wave directions. “Combining data from airplanes, drones, and boats allowed us to track the movements of thousands of jellyfish and use mathematical models to analyze their navigation strategies,” Dr. Lehahn explained.

Jellyfish navigate and respond to their environment without a brain! 🌊🧠 #Jellyfish #MarineLife #OceanMysteries #NatureFacts #Wildlife pic.twitter.com/vM9MBYBqPU

— Infinite Curiosities (@Infinite_Curios) August 10, 2024

Astonishing Findings: Jellyfish Navigate with Precision

The study revealed that Rhopilema nomadica jellyfish are not passive drifters but rather skilled navigators. They swim collectively at about 10 cm per second, deliberately moving westward against the prevailing waves. By swimming away from the coast, they significantly boost their survival chances, avoiding the hazardous shallows where they are often stranded and perish.

Interestingly, the jellyfish’s swimming direction can change depending on environmental factors. In strong tidal currents, they may swim against the current rather than the waves, adapting their strategy to avoid being swept onto beaches. In some scenarios, jellyfish might choose to stay near the coast, taking refuge in inlets or estuaries where conditions might be more favorable. “Their objective is simple: to reach environments that maximize their survival,” the researchers noted.

The Complex Dance Between Jellyfish and the Sea

Despite their navigational prowess, jellyfish still frequently end up stranded on beaches, particularly after storms. According to the researchers, this happens when strong currents and waves overpower the jellyfish’s swimming efforts. In calmer conditions, their direction and speed are governed almost entirely by their own movements. However, when powerful undertows develop, such as those following a storm, even the most skillful jellyfish are at the mercy of the sea.

We collaborate on a Jellyfish experiment with the Marine Biology Laboratory.#ANL #marinebiologists #marineresearch #jellyfish #MarineLife pic.twitter.com/4M45TPpdIp

— ANL Haifa (@anl_Haifa) July 14, 2024

“This study demonstrates that jellyfish do not merely drift; they have the ability to steer their course,” the researchers concluded. “Understanding these behaviors could one day enable us to predict when and where jellyfish will appear along our coasts, mitigating the impact of their invasions.”

The findings of this research represent a significant leap in our understanding of jellyfish, providing new insights into the complex interplay between these ancient mariners and the forces of the sea. As scientists continue to unravel the mysteries of jellyfish behavior, we inch closer to solving one of the ocean’s most enigmatic phenomena, with implications that stretch far beyond the scientific community.