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)

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)

A Tenggerese shaman praying for worshippers at Widodaren cave during the Tenggerese Hindu Yadnya Kasada festival on July 31, 2015 in Probolinggo, East Java, Indonesia. The festival is the main festival of the Tenggerese people and lasts about a month. On the fourteenth day, the Tenggerese make the journey to Mount Bromo to make offerings of rice, fruits, vegetables, flowers and livestock to the mountain gods by throwing them into the volcano's caldera. The origin of the festival lies in the 15th century when a princess named Roro Anteng started the principality of Tengger with her husband Joko Seger, and the childless couple asked the mountain Gods for help in bearing children. The legend says the Gods granted them 24 children but on the provision that the 25th must be tossed into the volcano in sacrifice. The 25th child, Kesuma, was finally sacrificed in this way after initial refusal, and the tradition of throwing sacrifices into the caldera to appease the mountain Gods continues today. (Photo by Ulet Ifansasti/Getty Images)

Ukrainians jump over a bonfire in Kiev, Ukraine, 06 July 2019, as they celebrate the traditional pagan holiday of Ivana Kupala. Ivana Kupala is celebrated, during the summer solstice, on the shortest night of the year, marking the beginning of summer and is celebrated in Ukraine, Belarus, Poland and Russia. People sing and dance around bonfires, play games and perform traditional rituals. Young people jump over bonfires in order to test their bravery. Couples holding hands jump over the flames to test their love. If the couple does not succeed it is predicted to split up. Traditionally, children and young unmarried women wear wreaths of wild flowers on their heads to symbolize purity. (Photo by Sergey Dolzhenko/EPA/EFE)

In this Wednesday, August 21, 1991 file photo, appreciative muscovites hand bread, sausages and flowers to a Soviet tank's driver who helped stop the failed hardline coup in Moscow, Russia. When a group of top Communist officials ousted Soviet leader Mikhail Gorbachev 30 years ago and flooded Moscow with tanks, the world held its breath, fearing a rollback on liberal reforms and a return to the Cold War confrontation. But the August 1991 coup collapsed in just three days, precipitating the breakup of the Soviet Union that plotters said they were trying to prevent. (Photo by Czarek Sokolowski/AP Photo/File)

A giant sculpture of a seven-month-old baby by artist Marc Quinn entitled “Planet” contrasts against the stately grandeur of Chatsworth House and the Derbyshire countryside on 4 September, 2008, Chatsworth, England. The bronze sculpture painted white is part of the Beyond Limits exhibition of modern and contemporary sculpture displayed in the gardens of Chatsworth by Sotherby's. More than 20 works will be on display from 9 September to 2 November 2008. In past years acclaimed artists Damien Hirst, Antony Gormley, Salvador Dali and Henry Moore have had work exhibited. (Photo by Christopher Furlong/Getty Images)

The artwork of Giant Horse Aboriginal rock art galleries in the Quinkan Country is seen on June 19, 2011 in Laura, Australia. The ancient aboriginal rock art in this region is some of the largest and oldest in the world, dating back over 15,000 years. Paintings, stencil art and engravings cover thelands traditionally home to the Kuku, Yalanji, Guugu Yimithirr and Kuku Thaypan people. As a UNESCO-identified top 10 rock art site in the world, international travelers visit the area to learn and understand the aboriginal culture through the artwork. (Photo by Mark Kolbe/Getty Images)

A man feeds a seagull during a record low tide in Saint Malo, western France, March 21, 2015. Towns on France's North Atlantic coast braced for their first giant tide of the millennium on Saturday as the full moon and this week's solar eclipse combined to create an ocean surge not seen since 1997. (Photo by Stephane Mahe/Reuters)