Manta Rays' Profound Descents Transform Approaches to Marine Navigation

Oceanic manta rays (Mobula birostris) are diving to depths beyond 1,200 meters to collect vital environmental information, overturning previous beliefs about their habits,

. By measuring temperature, dissolved oxygen, and possible geomagnetic changes during these deep descents, scientists believe the rays use the ocean’s depths as a “vertical scan” to help them navigate and determine if they should move to new feeding areas. The research, which involved satellite tracking of 24 manta rays in Indonesia, Peru, and New Zealand, reveals a surprising level of complexity in how these animals interact with their surroundings. Nearly 47,000 dives were documented, with 79 labeled as “extreme” (deeper than 500 meters). The rays plunged at rates reaching 2.9 meters per second—much faster than a human swimmer—paused briefly at depth, and then returned to the surface. Importantly, these dives did not show the extended bottom periods or repeated movements typical of hunting. Instead, the evidence points to the dives being used for gathering environmental information. After such deep dives, manta rays frequently traveled hundreds of kilometers in a deliberate, investigative manner, . These deep excursions come at a physiological cost. In the cold, low-oxygen depths, manta rays—being ectothermic—experience rapid body cooling. Scientists propose that the rays reduce their time in these harsh conditions by descending quickly and possibly relying on anaerobic metabolism or temporarily limiting gill function, similar to the “breath-holding” behavior seen in some shark species. Long periods at the surface before and after dives likely help the rays recover, rewarm, and prepare for their next deep journey. Regional differences also highlight the intentional nature of these dives. The majority of extreme dives were recorded in New Zealand, where manta rays move beyond the continental shelf into much deeper waters. Conversely, those in Indonesia and Peru stayed in shallower coastal regions, with extreme dives occurring mainly when leaving the shelf. Statistical analysis showed that the distance from the shelf edge was a strong predictor of these deep dives, . Although the study stops short of proving that manta rays use geomagnetic cues for navigation, evidence from other marine animals such as sharks and sea turtles supports this possibility. The researchers also highlight unresolved issues: What is the energy cost of these dives? Do they align with features like thermoclines or underwater mountains? Might they serve to communicate with other rays or assess habitat conditions? “These dives reveal a hidden dimension of their existence,” the authors commented. “What we see at the surface is just a glimpse of their full story.” The research not only changes our understanding of manta ray behavior but also , challenging the idea that deep dives are only for hunting or escaping predators.