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)

Rescuers attempt attempt to push stranded whales back into the ocean at Ujong Kareng beach in Aceh province, Indonesia, Monday, November 13, 2017. An official said a small pod of whales was stranded at the beach and attracted hundreds of onlookers who posed for pictures with them. (Photo by AP Photo/Zulkarnaini)

An Israeli 155mm self-propelled howitzer, loaded on a trailer, arrives at a position along the Israel-Gaza border on May 13, 2021. Israel deployed additional troops to Gaza's border as the military conflict with Palestinian Islamists raged on, while inside Israel security forces scrambled to contain deadly riots between Jews and Arabs. (Photo by Emmanuel Dunand/AFP Photo)

Children riding on donkeys queue to fill their jerrycans with water from a cistern at a make-shift camp for the internally displaced in Yemen's northern Hajjah province on July 12, 2021, amidst an extreme heat wave and severe water shortage. (Photo by Essa Ahmed/AFP Photo)

A child is pictured with the face covered in blood during a religious procession to mark Ashura in Nabatieh, southern Lebanon on August 19, 2021. (Photo by Aziz Taher/Reuters)

A fisherman struggles to push a wheelbarrow full of sharks that have just been dropped off a pirogue on the beach of Songolo, the fishing district of Pointe-Noire in the Republic of the Congo in November 2021. Many artisanal fishing crews on the Congolese coast specialise in shark fishing (Photo by Marco Simoncelli/Al Jazeera)

German troops in Stalingrad, USSR. September 10, 1942. (Photo by TASS)

A woman from the Hui Muslim community carries food that will be eaten by her and others to break their fast during the holy fasting month of Ramadan at the Nanxiapo Mosque on June 8, 2018 in Beijing, China. (Photo by Kevin Frayer/Getty Images)