The investigation involved a diverse dataset covering 19 species across 17 geographically distinct locations worldwide. Through a detailed assessment of 199 separate events, the research team identified that approximately one-quarter of these interactions were genuinely mutual, involving reciprocal social or playful behavior. This finding counters the long-held belief that dolphins primarily harass or exploit the larger whales. Notably, for humpback whales, nearly one-third of observed encounters featured positive behavioral responses to the dolphins, including active engagement and displays suggestive of social bonding.

Humpback whales, which accounted for the majority of the documented interactions, exhibited several intriguing behaviors indicative of social openness. These activities included rolling side to side and belly presentation, gestures often interpreted as courtship or friendly socializing within marine mammal communities. Moreover, the whales appeared to strategically approach dolphins, maneuvering their heads and rostrums in ways that suggest a deliberate intention to interact, rather than evade or ignore. Importantly, avoidance behaviors were seldom observed, further underscoring the potential for genuine social connection between these species.

In contrast to assumptions that dolphins are persistent pests during their encounters with whales, the research highlights a complex interplay characterized by nuanced behavioral signaling. Co-author Olivia Crawley emphasized the unique opportunity these observational studies provide to unravel the subtleties of interspecies communication. Through the careful cataloging of behavioral patterns, including characteristic dolphin acts such as bow riding and gentle physical contact, the study offers a foundational platform for future investigations into the sociobiology of marine mammals.

The researchers took a comprehensive approach to data collection, documenting parameters such as species identity, interaction location, temporal context, the number and age class of individuals involved, and the precise spatial relationship between dolphins and various whale body parts, including the rostrum, flanks, and flukes. This granularity allowed for a deeper understanding of the behavioral ecology at play. Bow riding, where dolphins swim near the whale’s rostrum, emerged as the most prevalent form of interaction. This behavior is believed to confer energetic benefits for the dolphins, leveraging the hydrodynamic wake generated by the whale and thus potentially representing a form of one-sided play or opportunistic behavior.

Within the compiled dataset, the baleen whales included six species, prominently dominated by humpbacks at 68%, followed by grey whales at 16%, and fin whales comprising 7%. The observers recorded an estimated total of 1,570 dolphins, with bottlenose dolphins forming the majority (51%), alongside common dolphins (17%) and Pacific wide-sided dolphins (15%). An intriguing aspect was the presence of juvenile animals, with calves of both species included in several events, suggesting these interactions may have developmental or social learning components.

Individual whale species exhibited distinct behavioral patterns in response to dolphins. Humpback whales frequently moved their pectoral fins towards the dolphins—a potential invitation for interaction or a tactile communication method—while grey whales were more often observed rolling. Southern right whales displayed pectoral slaps in half of the few documented events. Aggressive responses such as tail slaps, a known antagonistic behavior, were comparatively scarce, particularly among humpback whales, indicating that aggression is not a predominant feature of these encounters.

A spectacular new insight emerged from two videos obtained via suction camera tags affixed to humpback whales. These high-resolution, close-proximity recordings revealed dolphins accompanying humpbacks not only at the surface but extending their interactions to the ocean floor. This continuous and intimate association hints at a degree of social play or cooperative behavior hitherto undocumented in such depth and complexity. The possibility of dolphins and whales engaging in tactile social play underwater represents a cutting-edge frontier in marine ethology.

Dr. Meynecke pointed out that social play among marine mammals often entails mutual cooperation and reciprocity. However, the study also distinguishes cases of one-sided play, where only one species appears to engage in playful behavior, while the other might be indifferent or even annoyed—such as dolphins teasing whales during feeding events. This duality enriches our understanding of cetacean social interaction, encompassing both cooperative and competitive elements within these interspecies engagements.

From a broader ecological perspective, the study underscores the importance of behavioral research in revealing the embedded complexity of marine ecosystems. The interactions between baleen whales and dolphins not only provide insight into their social structures but also impact energetic dynamics and habitat use patterns. These findings could inform conservation strategies by illustrating how species coexist and influence each other within shared environments, emphasizing the need for integrated ecosystem management approaches.

The extensive collaboration between scientists, citizen scientists, and tourism operators underscores the value of multidisciplinary and multi-source data aggregation in advancing marine mammal research. By leveraging hundreds of publicly sourced videos and photographs alongside scientific observations, the study exemplifies a modern approach to behavioral ecology that is inclusive and scalable. This methodological innovation paves the way for future advances in understanding complex animal behaviors in the wild, particularly those that occur underwater and are difficult to observe directly.

Finally, the researchers hope their work ignites further interest and studies exploring the multifaceted social lives of marine mammals. Beyond expanding academic knowledge, these revelations captivate the public imagination by portraying whales and dolphins not just as distant oceanic giants but as socially sophisticated beings engaging in behaviors reminiscent of play and friendship. Such narratives are vital in fostering public support for conservation and marine ecosystem protection, amplifying the cultural and scientific value of these charismatic species.

Subject of Research: Social behavior and interactions between baleen whales (Mysticeti) and dolphins (Delphinidae)

Article Title: Assessing social behaviour between baleen whales (Mysticeti) and dolphins (Delphinidae)

Web References:
http://dx.doi.org/10.1007/s44338-025-00099-2

Image Credits: Olaf Meynecke

Keywords: baleen whales, dolphins, cetacean interactions, humpback whales, marine mammal behavior, social play, bow riding, mutualism, marine ecology, behavioral study, suction camera tags, interspecies interaction

The team’s observational study, recently published in Frontiers in Conservation Science, captures a detailed picture of seafloor disturbances caused by anchor deployment and retrieval across 36 Antarctic sites during the austral summer season of 2022-23. Using underwater camera systems positioned strategically near the sea floor, midwater, and surface, researchers recorded striking evidence of mechanical scouring. The footage reveals characteristic striations and grooves etched into the ocean substrate—hallmarks of heavy chain dragging as anchors were deployed or pulled up. In many cases, these physical alterations corresponded with a marked reduction or complete absence of benthic fauna, indicating severe habitat disruption.

Analysis of these affected zones showed that species typical of Antarctic benthic ecosystems, including slow-growing sessile organisms such as sponges, were either crushed or missing entirely within the disturbed patches. This contrasts sharply with adjacent undisturbed areas where marine life thrived, suggesting a localized but profound impact. The ecological significance of this loss cannot be overstated. For example, giant volcano sponges observed near the damaged sites are believed to be some of the oldest animals on Earth, potentially surviving for up to 15,000 years. These sponges contribute critically to oceanic carbon sequestration, water filtration, and habitat complexity, all vital functions sustaining the Antarctic marine food web.

Marine ecologist Matthew Mulrennan, founder of the ocean conservation nonprofit KOLOSSAL and the study’s lead author, emphasizes the broader consequences. “The damage observed isn’t just physical scarring—it’s a disruption of entire ecological processes,” Mulrennan explains. “These sponges and other benthic species support a diversity of life, including fish, crustaceans, and even penguins and seals. When such foundational species are disturbed, the effects cascade through the ecosystem, threatening biodiversity and the resilience of Antarctic waters.”

The prevalence of ship anchoring in Antarctica is increasing alongside growing human activity and interest in this remote frontier. Despite cold temperatures and harsh conditions, at least 195 vessels—including private yachts, research ships, and fishing boats—were recorded operating at anchorable depths of up to approximately 82.5 meters during the 2022-23 season. However, the true extent of anchoring may be underreported due to ships without proper licenses or monitoring. This growing maritime footprint amplifies concerns about cumulative damage and limited recovery opportunities for the slow-recovering Antarctic benthic communities.

Marine geophysicist Dr. Sally Watson, co-author of the study, underscores the concern regarding recovery times in polar environments. “Cold-water species are characteristically slow-growing and sensitive to physical disturbances,” she notes. “In some tropical coral reef systems, anchor damage can linger visually and ecologically for over a decade. In muddy Antarctic sediments, scars made by anchors may persist even longer, given the reduced biological activity and slow sedimentation rates at these latitudes.” Such protracted recovery periods highlight the urgent need for precautionary management measures.

Complicating mitigation efforts is the lack of comprehensive data on anchoring frequency and spatial distribution in Antarctica. Without robust databases or real-time tracking of vessel anchoring behavior, it remains difficult to quantify the scale of seafloor disturbance or to prioritize areas under threat. This gap poses a fundamental challenge for policymakers tasked with balancing the protection of sensitive habitats with growing maritime operations for scientific research, tourism, and resource exploitation in the region.

Ecological consequences aside, anchoring in Antarctic waters also poses risks to critical infrastructure such as undersea cables and pipelines. Damage to these installations could have cascading effects, disrupting communication networks and power supplies that depend on reliable subsea connectivity. Such indirect impacts elevate the stakes of unregulated anchoring activities, positioning the issue as not only an environmental concern but also one of economic and strategic importance.

The documented footprint of ship anchoring in the Antarctic seabed aligns it with other recognized forms of human-induced seafloor disturbance, such as bottom trawling. According to the researchers, anchoring may be an underestimated contributor to habitat degradation on a global scale, deserving equal attention and regulatory oversight. This under-recognition stems largely from the invisible nature of the damage; unlike visible coastal impacts, anchoring scars lie beneath the waves, out of sight and consequently out of mind for many stakeholders.

Given these compelling findings, the research team advocates for enhanced monitoring and stricter regulations governing anchoring in Antarctic waters. Management strategies could include restricting anchoring to designated zones, mandating the use of environmentally sensitive mooring technologies, or implementing real-time vessel tracking systems to avoid sensitive benthic habitats. Moreover, ongoing scientific research is needed to better understand the full ecological ramifications, recovery trajectories, and potential restoration techniques suitable for cold-water benthic ecosystems.

The revelations brought forward by this first-ever video documentation of Antarctic anchoring damage form a critical call to action for ocean conservation globally. As the Antarctic region faces mounting pressures from human activity and climate change, safeguarding these ancient and complex marine habitats becomes increasingly urgent. Recognizing anchoring as a significant anthropogenic disturbance allows for targeted efforts to mitigate harm, preserving biodiversity and ecosystem services vital to planetary health.

This study not only fills a prominent knowledge gap in polar marine ecology but also serves as a stark reminder that even seemingly routine maritime operations have the potential for profound environmental impact. The fight to protect Antarctica’s seafloor ecosystems demands coordinated international attention, integrating scientific insights with governance to ensure that these remote marine wildernesses remain vibrant for generations to come.

Subject of Research: Not applicable

Article Title: Anchor and Chain Damage to Seafloor Habitats in Antarctica: First Observations

News Publication Date: 9-Jun-2025

Web References:
10.3389/fcosc.2025.1500652

Image Credits: Matt Mulrennan / KOLOSSAL

Keywords: Antarctic seafloor, ship anchoring, marine habitat damage, benthic ecosystems, underwater video evidence, ecological disturbance, slow-growing sponges, marine conservation, ocean floor impact, habitat recovery, maritime regulation, cold-water ecosystems