Marine Science in a Drop

PENGUINS CAUGHT ON CAMERA EATING "SEA BUTTERFLIES"

For the first time, researchers have captured video evidence of Adélie penguins actively feeding on shelled pteropods, tiny, free-swimming sea snails, in East Antarctica. The team equipped eight chick-rearing penguins with cameras and GPS loggers. Over 86 hours of footage revealed that seven of the eight birds consumed pteropods, with two individuals deriving over 60% of their prey from Clio pyramidata and Limacina rangii. While krill remained the dominant food source, the penguins opportunistically targeted dense pteropod patches, suggesting this overlooked trophic pathway may serve as an important supplemental prey.

- Pteropods found and consumed by Adélie penguins A solitary Clio pyramidata. B aggregated C. pyramidata in the water column. C a capture event of C. pyramidata and D a capture event of Limacina rangii.

This discovery carries significant climate implications. Shelled pteropods are highly vulnerable to ocean acidification caused by fossil fuel emissions, and their availability could shift as Southern Ocean chemistry changes. The study is limited to one colony and one season, but it raises critical questions: will Adélie penguins increasingly rely on pteropods as a fallback food, or will acidification collapse this emerging link? Future research will explore whether this behavior persists across years and colonies, or only emerges under specific environmental pressures.

Reference: Watanabe et al. 2026. Video evidence of pteropod predation highlights diet flexibility in Adélie penguins. Marine Biology. 

FIRST-EVER VIDEO EVIDENCE CONFIRMS HEADBUTTING IN SPERM WHALES

Researchers have documented sperm whales headbutting each other using drone footage, confirming a behavior long speculated about from 19th-century whaling accounts. The study recorded three observations in the Azores and Balearic Islands where sub-adult whales collided at speeds up to 3.6 m/s, generating forces of approximately 200 kN. The individuals involved were younger whales, not the massive adult males previously hypothesized to engage in such contests.

These findings challenge previous skepticism that headbutting would risk damaging the whales' complex sound-producing anatomy. The behavior may function as rough play for practicing adult competition or play a role in social dynamics, such as the dispersal of maturing males from their natal groups. The opportunistic drone observations suggest such near-surface behaviors may be more common than previously recognized.

Gif: Headbutting behavior between two juvenile sperm whales. 4x speed. Full video here

SOUTHERN RIGHT WHALES OBSERVED ENGAGING IN SAME-SEX SEXUAL BEHAVIOR IN URUGUAYAN WATERS

New scientific research has documented the first audiovisual evidence of male-male genital penetration among southern right whales (Eubalaena australis). The discovery occurred during the 2024 monitoring season in Uruguay's Maldonado department, where drone footage captured four distinct events involving adult males. Initially interpreted as typical mating behavior, detailed analysis revealed the interactions occurred between same-sex individuals. The findings were published in Marine Mammal Science.

Southern right whales possess a polygynandrous mating system where males compete through endurance and sperm production rather than physical aggression. The observed behaviors occurred without signs of force or resistance, suggesting these interactions serve functions beyond direct reproduction. Researchers propose that such encounters may facilitate practice of reproductive skills, social bonding, and tension reduction. These activities could be particularly relevant for younger males developing the maneuvering abilities needed for successful mating with females.

The study highlights the significance of Uruguayan coastal waters as a socialization and mating area for the species, distinct from traditional calving grounds. The research exemplifies how collaboration between field observers, photographers, and scientists can yield novel observations about animal behavior. These findings contribute to understanding the complexity of social and sexual interactions in marine mammals and underscore the importance of continued research in regions where these behaviors occur.

ANCIENT BRAZILIAN WHALERS HUNTED GIANTS 5,000 YEARS AGO

A groundbreaking study reveals that Indigenous people living on the coast of southern Brazil were hunting giant whales a staggering 5,000 years ago. This discovery, based on analyzing bone tools and remains in museum collections, pushes back the origins of systematic whaling by over a thousand years, challenging the long-held belief that this complex practice began only in the Arctic. The research shows that the Sambaqui people, far from being simple coastal foragers, possessed sophisticated maritime technology, crafting harpoons from whale bone to target massive animals like southern right and humpback whales. This redefines our understanding of their society, marking them as one of the earliest known whaling cultures in the world.

The findings also provide a crucial window into the ocean's past, illuminating whale populations long before industrial hunting decimated them. By identifying humpback whale remains, the study offers the first concrete evidence that these whales once inhabited these southern Brazilian waters, information vital for modern conservation efforts. This story, preserved in shell mounds and museum drawers, underscores a profound and ancient relationship between humans and the sea. It highlights a deep-seated Indigenous maritime knowledge that flourished for millennia, an unwritten history now being recovered through the power of modern science.

LEOPARD SEAL MOTHERS CARE FOR THEIR DECEASED PUPS FOR DAYS

Scientists have uncovered a profound and prolonged display of maternal grief in leopard seals, in Chilean Patagonia. For the first time, researchers documented a "postmortem attentive behavior," where mothers were observed carrying, guarding, and nurturing their deceased pups for extended periods. In an extraordinary case, one mother seal exhibited this behavior for over 20 days, the longest recorded in any seal species and among the longest for any mammal. Even more striking, the same female was seen repeating this heartrending ritual across three separate years, suggesting a deep, consistent maternal bond that challenges our understanding of this normally solitary creature.

This rare behavior, more commonly associated with socially complex animals like orcas and elephants, presents an evolutionary puzzle. Why would a mother invest so much energy in a lost cause? A necropsy on one pup pointed to emaciation as the cause of death, indicating it likely never nursed successfully. The findings raise critical questions: is the unstable glacial habitat in their Patagonian pupping grounds unsuitable for raising young, or are other factors like genetics or maternal inexperience at play? This discovery opens a new window into the hidden emotional and reproductive lives of leopard seals, highlighting the urgent need to understand the challenges they face in a rapidly changing polar environment.

FIRST AT-SEA CONFIRMATION OF THE GINKGO-TOOTHED BEAKED WHALE

For years, a mysterious echolocation pulse known by scientists as BW43 echoed through the deep waters of the North Pacific. Now, a landmark 2024 expedition off the coast of Baja California has finally cracked the case. Researchers successfully sighted, recorded, and genetically sampled a group of beaked whales, confirming the producer of the BW43 pulse is the equally enigmatic ginkgo-toothed beaked whale (Mesoplodon ginkgodens). This is the first time this species has ever been definitively identified and studied alive in the wild, linking its genetic, acoustic, and visual identity.

-A juvenile/subadult ginkgo-toothed beaked whale.

For the first time, scientists describe the whale's at-sea appearance, noting how juveniles are pale gray with a distinctive dark eye patch, while adult males develop a diagnostic white-tipped beak. Photographs of adult males showed extensive scarring from combat with other males. Previously known in the eastern Pacific from only two strandings over 70 years, the ginkgo-toothed beaked whale was considered a vagrant. Now, by mapping the widespread BW43 detections, we know it is a resident species from California to Baja California.

main photograph: young adult male ginkgo-toothed beaked whale swims along with the same adult male.

A DEEP-SEA ANEMONE BUILDS A HOME FOR ITS HERMIT CRAB HOST

Japan researchers have identified a new species of sea anemone, Paracalliactis tsukisome, which engages in a sophisticated symbiotic relationship with the hermit crab Oncopagurus monstrosus, collected at 300 m depth, in the Sea of Kumano. Unlike typical anemones, this soft-bodied animal performs an astonishing feat of bio-engineering: it secretes a hard, shell-like structure named carcinoecium.

-Enlarged view of the column of Paracalliactis tsukisome, indicating the tubercles forming a weak corona.

This relationship is mutualism, where both partners reap significant benefits. Stable isotope analyses revealed the anemone feeding strategy: it consumes suspended organic particles from the water and, remarkably, recycles the host crab's faeces. This efficient use of available nutrients is a key adaptation to the deep sea. In return, the hermit crab gains a substantial survival advantage. Data shows that crabs in this partnership grow larger than their relatives, a direct indicator of improved fitness and health, all thanks to the superior housing provided by their symbiotic partner.

3D micro-computed tomography scans showed that the anemone attaches to the shell in a consistent, unidirectional pattern, always positioned near the aperture. It is likely adaptation to optimize access to food resources and facilitate the precise secretion of the hermit crab. The discovery provides the first quantitative evidence for mutualism in such shell-forming associations.

The specific name ‘tsukisome’ is a classical Japanese word referring to a pale pink color, historically associated with the hue of the Japanese crested ibis. It appears in a poem within the Man'yōshū, the oldest surviving anthology of Japanese poetry. In this poem, a kimono dyed in ‘tsukisome’ symbolizes half-hearted or fickle affection, with the poet declaring, ‘I won’t meet you with a half-hearted affection like the pale pink hue of a kimono’. This name aptly reflects the new species’ pale pink coloration while ingeniously inverting the poem's original meaning. Rather than symbolizing fleeting feelings, the name evokes the deep, faithful, and species-specific symbiotic bond between the anemone and its hermit crab host.

EXTREME CRITICALLY ENDANGERED VAQUITAS ARE HAVING BABIES

The 2025 vaquita survey conducted by Sea Shepherd and CONANP Mexico confirms that the vaquita, the world's most endangered marine mammal, is fighting for survival. Researchers estimate a small group of at least 7 to 10 individuals remains, with evidence of recent reproduction including new calves and healthy juveniles. Most significantly, the survey shows no signs of the rapid population decline witnessed in previous years. The footage was obtained within the protected Zero Tolerance Area, a gillnet-free sanctuary that provides a vital refuge for the remaining vaquitas.

Crucially, the survey reveals that vaquitas are now regularly venturing beyond the protected Zero Tolerance Area into northwestern waters, where illegal gillnets make the area deadly. The survival of these last vaquitas, particularly vulnerable mothers and calves, now depends on urgently extending conservation efforts to protect these newly identified habitats. Immediate action is needed to safeguard the species' remaining foothold.

video drones by Fabian Rodriguez/ Sea Shepherd Conservation Society/ CONANP

CUSK-EEL SANCTUARY SPOTTED AT DEEP-SEA METHANE SEEP OFF CHILE

A recent expedition off the Chilean coast has revealed dozens of red cusk-eels (Genypterus chilensis), nestled within a dense grove of tube worms at a methane seep. This marks the first documentation of these commercial fish adopting a chemosynthetic ecosystem as their habitat. Intriguingly, high-definition video footage suggests the eels may be visiting this otherworldly landscape for a specific service: parasite removal by resident spider crabs, pointing toward a complex symbiotic relationship in the abyss.

This discovery fundamentally challenges our understanding of methane seeps. Rather than existing as isolated biological islands, these environments appear deeply connected to broader ocean systems, serving as potential hubs for species targeted by fishing fleets. The finding carries significant urgency, as the red cusk-eel is considered vulnerable to overfishing. The surrounding seafloor was littered with lost fishing gear, a silent testament to the fact that this newly studied scientific wonder may already be known to local fishermen, placing it directly in the path of human activity.

The implications for conservation and fishery management are profound. If these seeps function as essential cleaning stations or spawning grounds, their protection becomes critical for sustaining fish populations. Researchers emphasize this two-day glimpse represents just the beginning; the full ecological story throughout the seasons remains unknown. This discovery serves as a powerful reminder that the deep sea still holds profound mysteries, and its protection is inextricably linked to the health of the ocean resources upon which we depend.

Reference: Levin et al., 2025. Congregation of cusk‐eels (Genypterus chilensis, Ophidiiformes) at a deep‐sea methane seep off Chile. Ecology

RESEARCHERS FIND SEABIRDS DEFECATE ONLY WHILE FLYING

Seabirds are not only important predators in the open ocean, they also move nutrients through their droppings. A new study of streaked shearwaters (Calonectris leucomelas) in Japan has revealed that these birds almost never defecate while resting on the sea surface. Instead, they excrete during flight, and at a regular pace of every four to ten minutes. Using small cameras attached to the birds, researchers found that a single shearwater can release about five percent of its body weight in droppings per hour.

This behaviour could have wider consequences for the marine environment. Much like whales, which are known to recycle nutrients through the so-called “whale pump,” seabirds may fertilise the ocean as they travel. With hundreds of millions of shearwaters and related species across the globe, their excretion could influence plankton growth and, in turn, the food webs that support fish and other marine life. The study highlights how even a basic behaviour, such as where and when birds relieve themselves, can shape the functioning of entire ecosystems.

Reference: Uesaka & Sato. 2025. Periodic excretion patterns of seabirds in flight. Current Biology

Streaked shearwater dropping recorded with a belly-mounted video camera by Uesaka & Sato.

A newly discovered deep-sea limpet, Bathylepeta wadatsumi, found at a record depth of 5,922 metres off the coast of Japan, has been named after Wadatsumi, the sea god of Japanese mythology and the towering monk from the manga ONE PIECE. This large true limpet (up to 40.5 mm) was observed grazing on sediment-covered volcanic rock using the manned submersible Shinkai 6500.

In situ imagery at the type locality of Bathylepeta wadatsumi, 500 km southeast of Tokyo, Japan.

SCIENTISTS UNCOVER A NEW SPECIES OF MANTA RAY IN THE ATLANTIC OCEAN

For over fifteen years, scientists suspected that a mysterious species of manta ray was hiding in plain sight in the Atlantic Ocean. Often confused with its close relatives, the oceanic manta ray and reef manta ray, this elusive animal was finally confirmed and formally described as a new species: Mobula yarae. Through a careful combination of genetic studies and physical comparisons, researchers showed that this species forms a distinct evolutionary lineage. It has unique features, including a striking V-shaped mark behind its gills, a special kind of skin denticle shaped like a star, and a small residual spine embedded near its tail. These traits, along with its DNA, make it unmistakably different from other known manta rays.

The newly Atlantic Manta Ray Mobula yarae lives only in the Atlantic coast of the Americas, and seems to prefer warm coastal and estuarine waters. Juveniles have been spotted along the Amazon coast, in Florida, and around the oceanic islands of Brazil. Adults, on the other hand, are more common around the Yucatán Peninsula and the southeastern United States. Sadly, this new species is already facing serious threats. It is often caught by accident in fishing gear, hit by boats, tangled in lines, and exposed to growing coastal pollution. These dangers are made worse by the fact that Mobula yarae looks so much like other manta rays, making it difficult to protect unless it is properly identified.

-Distinct colouration of manta ray species. Dorsal and ventral colouration pattern of Mobula birostris a, d, Mobula alfredi b, e, and Mobula yarae c and f.

The name yarae comes from Yara, a mythical figure from the Indigenous Tupi and Guaraní cultures. Yara is known as the mother of the waters, a powerful spirit of beauty and protection. Naming this ray after her is both a tribute and a call to action. The formal recognition of Mobula yarae opens the door for targeted conservation efforts. With its unique traits, restricted Atlantic distribution, and vulnerability to multiple human pressures, this species qualifies for urgent assessment under international and national conservation frameworks. Ensuring accurate identification and monitoring will be essential to prevent further decline and to secure the long-term survival of this newly described manta ray.

Photographs: Sean Rowan Laughlin

MAGELLANIC PENGUINS MAY RIDE OCEAN CURRENTS TO SAVE ENERGY ON LONG JOURNEYS

New research published reveals that Magellanic penguins (Spheniscus magellanicus) may be far more sophisticated navigators than previously thought. By tracking 27 adult penguins from a colony in Península Valdés, Argentina, scientists discovered that these seabirds adjust their travel routes in response to ocean currents. In calm waters, the penguins swim directly toward their colony. But when facing stronger currents, they shift their paths to move with the flow, even if it means taking a longer route, ultimately conserving energy during long-distance foraging trips.

The study suggests that Magellanic penguins can detect current drift and correct their trajectories even when the coastline is out of sight. This implies a remarkable ability to integrate environmental cues and maintain efficient navigation over open ocean. While the findings are based on a single foraging trip per bird, they raise important questions about how other marine animals might also exploit dynamic ocean features like tidal flow to optimise their movements.

Photo by Frank Dietze

OCEAN WARMING DISRUPTS ANGELSHARK MATING IN THE CANARY ISLANDS

Angelsharks (Squatina squatina), listed as Critically Endangered are showing adverse behaviour related to climate change. Females are avoiding traditional mating grounds during periods of unusually high ocean temperatures, prioritising cooler waters instead. This female absence, documented in La Graciosa Marine Reserve during the 2022 breeding season, contrasts with the continued presence of males, suggesting an increasing mismatch in the species’ reproductive patterns.

The study, led by Lancaster University and the Angel Shark Project: Canary Islands, found that temperatures above 22.5 °C throughout much of autumn and winter may exceed the thermal tolerance of females. Using acoustic telemetry, researchers tracked more than 100 individuals between 2018 and 2023, revealing a clear link between female presence and sea temperature.

These findings highlight the angelshark’s vulnerability to extreme events linked to climate change, particularly in regions like the Canaries, which already represent the species’ thermal distribution limit. The authors stress the urgent need to protect key habitats and maintain long-term monitoring to mitigate the impacts of ocean warming on threatened marine species.

Reference: Mead et al. 2025. Rapid Ocean Warming Drives Sexually Divergent Habitat Use in a Threatened Predatory Marine Ectotherm.” Global Change Biology

UNMASKING THE BLUEBOTTLE REVEALING FOUR DISTINCT SPECIES THROUGH GLOBAL CITIZEN SCIENCE

For over two centuries, the Portuguese man o’ war (Physalia spp) was considered a single, cosmopolitan species, drifting across the world’s oceans and stinging unsuspecting swimmers. But new genomic research has overturned this long-held view, revealing that Physalia is not one species, but at least four: P. physalis, P. megalista, P. utriculus, and a newly described species, P. minuta. Researchers sequenced the genomes of 151 specimens from around the globe and found strong reproductive isolation between genetic lineages, even when their distributions overlap. This evidence aligns with historical descriptions from the 18th and 19th centuries, which proposed several species that were later dismissed due to limited data.

Crucially, the study integrated over 4,000 photographs from iNaturalist, using citizen science to match distinct morphologies with genetic lineages. These images, contributed by amateur naturalists, swimmers, and lifeguards, allowed researchers to confirm physical differences that earlier taxonomists could not consistently observe due to preservation challenges. The result is a rare success story in which modern genomics, historical records, and participatory science come together to clarify the taxonomy of one of the ocean’s most recognisable creatures.

The discovery not only rewrites the story of Physalia but also challenges assumptions about biodiversity in the open ocean, reminding us that even the most visible marine life can hold hidden complexity, and that everyone, from sailors of the past to today’s citizen scientists, has a role to play in uncovering it.

KILLER WHALES CRAFT KELP TOOLS FOR SOCIAL GROOMING

In a remarkable discovery, researchers have documented wild Resident killer whale (Orcinus orca ater) manufacturing and using tools in a social context. Observed in the Salish Sea from April to July 2024, members of the endangered southern resident population were seen detaching short lengths of bull kelp (Nereocystis luetkeana) and using them during tactile interactions with a partner, a behavior the authors call allokelping. This behaviour differs from playful kelp draping commonly seen in cetaceans, whales in this study deliberately fashioned kelp segments using their teeth, positioned them between their bodies, and coordinated their movements to roll the kelp across one another’s skin.

This represents a potential case of tool-assisted allogrooming, a behaviour rarely documented in non-primates and never before in marine mammals. Statistical analyses suggest that allokelping may serve both hygienic and affiliative functions, being more common among close kin and individuals of similar age, and possibly linked to skin molting. The whales’ use of their entire bodies, rather than limbs, to manipulate the kelp, and the mutual benefit of the interaction, make this a unique form of tool use in the animal kingdom. If confirmed, it would expand our understanding of cetacean intelligence, culture, and the evolutionary roots of cooperation.

Photo: Orca grasps a bull kelp stalk by the holdfast end and detaches a short stipe segment for use in allokelping.

BULL SHARK SWIMS 7,290 KILOMETRES IN RECORD MIGRATION

A recent study revealed that a female bull shark (Carcharhinus leucas) travelled at least 7,290 kilometres from the Mozambique Channel to Nigeria, crossing from the Indian Ocean into the Atlantic in what is now the longest recorded movement for this species. The finding was made possible by an acoustic transmitter implanted in South Africa in 2021 and recovered when the shark was captured near Lagos in July 2024. Bull sharks have long been considered coastal residents with relatively limited movements and a strong preference for warm, estuarine environments, making this ocean-crossing journey a remarkable exception that challenges previous assumptions about their ecology.

The shark’s route included passing through the Benguela upwelling, a major cold-water system along the coasts of South Africa and Namibia that has traditionally served as a biogeographic barrier for tropical species. Researchers suggest that climate change, by altering the temperature and dynamics of such systems, may be enabling new migratory pathways for widely distributed marine animals. In addition to expanding our understanding of bull shark ecological flexibility, this event highlights the value of large-scale acoustic tagging programmes and international collaboration in tracking the movements of highly mobile and potentially vulnerable species.

Main photographs: Bull shark by Ingo Rogalla. And fisherman from Lagos, Nigeria, reported capturing a female bull shark with an internal acoustictransmitter. The shark was originally tagged on 2 April 2021 at the St Lucia Estuary mouth on the east coast of South Africa. Photo credit: Mr. Akeem Kolawol.