Oceanic manta rays, known as the largest species of ray swimming our oceans, have long fascinated marine biologists due to their graceful movements and expansive habitats. Unlike many marine creatures famed for deep dives, such as sharks and tuna, the diving behavior of oceanic mantas has been less understood, particularly concerning extreme depths. Recently, a pioneering international research team ventured into uncharted waters of this species’ behavior, uncovering remarkable insights about how these majestic animals interact with their deep-ocean environment.
Spanning nearly a decade from 2012 to 2022, this extensive study took place across three exotic and ecologically vivid regions: Raja Ampat in Indonesia, the coastal waters near Tumbes in northern Peru, and the offshore zones adjacent to Whangaroa in northern New Zealand. With oceanographic variability and unique seafloor topographies, these locations provided an ideal natural laboratory to explore and compare the diving patterns of oceanic mantas under differing environmental conditions.
Key to this research was the deployment of specialized tags on 24 individual oceanic manta rays. These tags, equipped with pressure sensors and satellite transmitters, captured an unparalleled volume and granularity of depth data, recording dives in breathtaking detail every 15 seconds. Retrieving eight of these devices post-detachment enabled researchers to obtain high-frequency, high-resolution datasets, while satellite-linked tags provided valuable broader summaries. The scale and resolution of tag data, amounting to over 2,700 tag-days, mark a substantial leap in understanding manta ray biomechanics and behavioral ecology.
One of the most striking revelations was the discovery that oceanic mantas are capable of plunging to depths exceeding 1,200 meters—an extreme far beyond what was historically documented. In fact, 79 days of recorded activity featured such profound dives, predominantly observed in New Zealand’s deep offshore waters, where the continental shelf drops sharply and the abyssal environment presents an enticing, albeit mysterious, frontier.
Detailed temporal analysis showed that these deep dives often occurred within 24 hours of the ray moving from the continental shelf to the deep ocean. Intriguingly, the nature of the dives displayed a “stepped decline,” a pattern where the ray descended in incremental stages rather than a single continuous plunge. Additionally, the mantas spent minimal time at the maximal depths, suggesting these plunges are not principally for feeding or predator evasion, as might be typical in other species.
This behavioral pattern has led researchers to hypothesize that deep diving in oceanic manta rays serves a critical navigational function. The ocean’s deep layers offer a more stable and predictable environment in terms of physical parameters such as temperature, oxygen concentration, and notably, geomagnetic field strengths and gradients. It is posited that by sampling these variables at depth, manta rays may construct a sophisticated mental map that facilitates their extensive migrations across vast, featureless oceanic expanses.
The concept that geomagnetic cues aid marine navigation is supported by the stepped ascent and descent patterns observed, which may represent systematic “sampling” of magnetic gradients. Unlike surface waters subjected to rapid environmental fluctuations, deeper layers provide consistent magnetic and chemical signatures critical for long-distance orientation, an advantage for migratory species navigating thousands of kilometers.
Following their intense deep excursions, mantas exhibited prolonged surface recovery periods marked by stepped resurfacing behaviors. This was typically succeeded by sustained horizontal travel, sometimes covering over 200 kilometers in several days. Such extended movement consolidates the idea that these dives readjust the animal’s positional awareness before initiating extended transits, rather than serving as direct foraging or escape responses.
Comparative geographical analyses revealed stark contrasts between regions. Few extreme dives occurred in Raja Ampat and Peru, where oceanic mantas predominantly occupy shallow coastal and shelf waters. In Raja Ampat’s case, the largely shallow seas, punctuated by short deep corridors, may not necessitate regular deep navigation sampling. Conversely, New Zealand’s steep continental drop-offs compel mantas to engage in these deep dives to traverse offshore habitats, highlighting the adaptive significance of this behavior in particular oceanic settings.
This groundbreaking research enriches our understanding of oceanic manta rays’ life history, underscoring the intricate link between their physical diving capabilities and environmental navigation. Beyond biological curiosity, deciphering the mechanism of these deep dives holds profound implications for marine conservation, emphasizing the connectivity between coastal nursery grounds and offshore migration corridors, essential for preserving these vulnerable species.
Despite the study’s robust findings, researchers acknowledge limitations such as the relatively small tag sample size and the snapshot nature of the behavioral data. Continuous tracking methodologies and broader datasets are necessary to refine interpretations and verify hypotheses about the functional drivers of these extreme dives. Future investigations could also integrate oceanographic modeling and geomagnetic mapping to further unravel the integration of environmental cues in manta navigation.
This study also highlights the broader mystery of the deep ocean—a realm central to Earth’s climate regulation and global fisheries yet one marred by substantial knowledge gaps. By illuminating how oceanic manta rays interact with the deep sea, scientists are edging closer to unveiling the ocean’s complex biological and physical tapestry, emphasizing the urgent need for international collaborative efforts to safeguard these ecosystems.
Calvin Beale, the first author, who pursued this research during his PhD at Murdoch University, emphasizes the broader ecological message: the conservation of migratory species like manta rays hinges on protecting the continuum of habitats they rely upon, from shallow coastal zones to the vast, dark depths of the ocean. This study not only enhances scientific understanding but also beckons policymakers and conservationists to recognize and prioritize international cooperation for marine biodiversity stewardship.
In a world increasingly shaped by climate change and anthropogenic pressures, insights into the navigation and behavioral ecology of oceanic manta rays illuminate pathways for both science and society. Understanding the role of deep dives as more than mere foraging attempts but as sophisticated environmental sampling mechanisms reframes our appreciation of marine life’s adaptation to one of Earth’s most extreme and enigmatic habitats.
This compelling investigation published in Frontiers in Marine Science invites continued exploration into the depths of the ocean’s mysteries, with oceanic manta rays as ambassadors—a dynamic blend of biology, geophysics, and conservation science converging to reveal the ocean’s silent navigators and the profound complexity of life beneath the waves.
Subject of Research: Animals
Article Title: Deep diving behaviour in oceanic manta rays and its potential function
News Publication Date: 15-Oct-2025
Web References: https://doi.org/10.3389/fmars.2025.1630451
Keywords: oceanic manta rays, deep diving behavior, marine navigation, geomagnetic cues, deep ocean ecology, marine animal behavior, migration, oceanography, marine conservation
