Behaviour: Mammals category. Giant Gathering by Tony Wu, USA. Dozens of sperm whales mingled noisily off Sri Lanka’s northeast coast, stacked as far down as Tony could see. This was a congregation of dozens of social units, like a gathering of the clans. Aggregations like this could be a critical part of the whales’ rich social lives but are rarely reported. Some two thirds of the population was wiped out before commercial whaling was banned in 1986. This kind of major gathering could be “a sign that populations are recovering”, says Tony. (Photo by Tony Wu/Wildlife Photographer of the Year 2017)

Customers are seen in front of a shop that reopened in central Copenhagen, Denmark, 01 March 2021. Shops reopened after several months of closure due to the coronavirus COVID-19 pandemic. (Photo by Philip Davali/EPA/EFE)

A woman wearing a traditional costume attends the celebrations marking the National Flag Day and the Day of Kyrgyz national “Ak-kalpak” hat at the central Ala-Too Square in Bishkek on March 4, 2021. (Photo by Vyacheslav Oseledko/AFP Photo)

Tourists enjoy blooming cherry blossoms at China Pharmaceutical University on March 22, 2021 in Nanjing, Jiangsu Province of China. (Photo by Yang Bo/China News Service via Getty Images)

Artists dressed as Hindu gods reacts to the camera during the Bonalu festival procession in Secunderabad, the twin city of Hyderabad, on July 26, 2021. (Photo by Noah Seelam/AFP Photo)

People wade through a road flooded by heavy rain in Kurume, Fukuoka prefecture, western Japan, Saturday, August 14, 2021. Torrential rain pounding southwestern Japan triggered a mudslide early Friday that swallowed some people and was threatening to cause flooding and more landslides in the region. (Photo by Kyodo News via AP Photo)

An Afghan evacuee plays at a holding centre run by the Italian Red Cross, where she carries out a quarantine with others, in Avezzano, Italy, August 30, 2021. (Photo by Guglielmo Mangiapane/Reuters)

Shooting star by Tony Wu, US/Japan. Winner, underwater. The electrifying reproductive dance of a giant sea star. As the surrounding water filled with sperm and eggs from spawning sea stars, Wu faced several challenges. Stuck in a small, enclosed bay with only a macro lens for photographing small subjects, he backed up to squeeze the undulating sea star into his field of view. The dancing posture of spawning sea stars rising and swaying may help release eggs and sperm, or may help sweep the eggs and sperm into the currents where they fertilise together in the water. Kinko Bay, Japan. (Photo by Tony Wu/Wildlife Photographer of the Year)