In a new study of viral abundance over a short time frame in the Sargasso Sea, researchers found that almost all viruses with cyclical changes in abundance were most active at night – somewhat surprising when the team expected microbial behavior to pick up pace when light was available for photosynthesis. It turns out the viruses most busy at night were not infecting bacteria that perform photosynthesis, which are among the types of bacteria known to be infected by viruses. Instead, these overnight viral hosts were microbes that focus on consumption of other organic matter because they can’t produce their own food. The findings reveal another level of complexity of viral interactions with marine bacteria, opening the door to new questions about how these dances in the dark influence ecological services provided by the world’s oceans.

Thanks to a satellite that happened to be flying over the 2025 Kamchatka tsunami not long after it formed, researchers have unprecedented insights – even more than land-based tools could provide – into the development and spread of this catastrophic wave. The findings establish the satellite as a powerful new tool for constraining earthquake source processes, with important implications for understanding tsunami hazards and the dynamics of subduction zones. Tsunamis from large subduction earthquakes deep below the ocean are among the most severe natural hazards. These long ocean waves can travel thousands of kilometers from their point of origin – crossing entire ocean basins – and devastate distant coastlines. However, despite their catastrophic potential, the physics underlying tsunami generation and propagation remain poorly understood due to the reliance on land-based seismic geodetic data and distant deep-water sensors. On July 29, 2025, the magnitude 8.8 Kamchatka earthquake and resulting Pacific-spanning tsunami illustrated these challenges. Although traditional monitoring using coastal gauges and seafloor sensors captured part of the event, these methods were limited by sparse coverage and attenuation of short-wavelength waves.

Now, Ignacio Sepúlveda and colleagues present direct observations of the tsunami using the NASA/CNES Surface Water and Ocean Topography (SWOT) satellite, which happened to fly over the region roughly 70 minutes after the event began, offering high-resolution two-dimensional measurements of sea-surface height with centimeter-level precision. According to Sepúlveda et al., SWOT captured the full wavefield, including short-wavelength wave trains trailing the leading front. This revealed the directions, curvature, and wavelengths of the tsunami waves. Moreover, sensitivity analyses of the data reveal that the tsunami was generated within roughly 10 kilometers of the subduction-zone trench, which is an insight that is not possible to obtain using land-based measurements or seafloor sensors alone. By directly linking detailed, two-dimensional satellite observations of the tsunami’s dispersive wavefield to its near-trench source, the findings mark the first such high-resolution spaceborne evidence of tsunamigenesis.

For researchers interested in research integrity-related themes, author Ignacio Sepúlveda notes: “I strongly support open data and reproducible research, but I am more cautious about the growing role of non-peer-reviewed preprints, which can circulate findings before they have been adequately tested and validated. This practice can negatively impact the testing, validation and peer-review of a scientific discovery because it puts additional pressure on authors (i.e. publish before a pre-print without validation comes out). Without pre-prints, a discovery will be only delayed by a few months and because of a good reason: validation.”

In an unprecedented observation, researchers captured the birth of a sperm whale calf, documenting how 11 whales from two normally separate family groups coordinated closely to support the newborn for hours after its arrival. These findings offer quantitative evidence of direct communal caregiving in cetaceans and suggest that short-term, highly coordinated cooperation during critical moments like birth may play a foundational role in maintaining the complex social structures seen in sperm whale societies. The evolution of cooperation remains a fundamental question in biology, particularly among highly social, long-lived mammals such as toothed whales. Species like sperm whales exhibit remarkably intricate social systems, in which stable, matrilineal family units cooperate in activities such as foraging and communal caregiving. Birth represents a critical and high-risk moment for the animals, as whale calves require immediate support to survive, making it a uniquely revealing context for understanding cooperative behavior. However, studying these deep-diving creatures in the open ocean represents a significant challenge and direct observations of sperm whale births are exceedingly rare. As a result, the cooperative behavior in sperm whale births has long remained a mystery. 

Here, Alaa Maalouf and colleagues present a detailed, high-resolution analysis of a sperm whale birth by integrating drone video footage, machine learning, and long-term data on social relationships and kinship. In July 2023, off the coast of Dominica, Maalouf et al. observed 11 members of a known sperm whale social unit, comprising two typically separate and unrelated family groups, gathering unusually close to the surface. Although these subgroups are generally distinct in their foraging behavior and social associations, they formed a cohesive cluster as a birth unfolded. Using drone footage, the authors documented the 34-minute delivery of a calf, followed by a period of intense, coordinated activity in which multiple adult females surrounded the mother. According to the authors, in the hour after birth, the group displayed strikingly cooperative behavior; individuals from both family groups took turns physically supporting and lifting the newborn to the surface, likely assisting it in breathing. The entire unit remained tightly organized during this critical period. In addition, there were close passes by Fraser’s dolphins and brief interactions with pilot whales. Several hours after the birth, the sperm whale cluster gradually dispersed into smaller, more typical foraging groups.