A Buddhist nun walks along a path as a stupa is seen at a temple in Anuradhapura, Sri Lanka October 16, 2016. (Photo by Dinuka Liyanawatte/Reuters)

Ocean Rebellion activists dressed as Merpeople protest against bottom trawling during a demonstration ahead of the COP26 summit, in Glasgow, Scotland Britain, October 30, 2021. (Photo by Dylan Martinez/Reuters)

Women walk on a sidewalk in northern Tehran, Iran, Thursday, January 9, 2020. (Photo by Vahid Salemi/AP Photo)

A train attendant wearing a protective face mask stands on a train to Wuhan, at the railway station in Beijing, China, 29 March 2020. Wuhan, the epicenter of the coronavirus outbreak, partly lifted the lockdown allowing people to enter the city after more than two months. Chinese authorities eased the quarantine measures as cases of Covid-19 across China have plummeted, according to Chinese government figures. (Photo by Roman Pilipey/EPA/EFE)

A man runs to take cover as supporters of a Shiite group allied with Hezbollah fire weapons during armed clashes that erupted during a protest in the southern Beirut suburb of Dahiyeh, Lebanon, Thursday, Octoner 14, 2021. It was not immediately clear what triggered the gunfire, but tensions were high along a former civil war front-line between Muslim Shiite and Christian areas. (Photo by Hassan Ammar/AP Photo)

Men from the Kenyan Maasai tribe perform a traditional jumping-ritual among fellow members of a common age-set as they observe a rite of passage to mark the transition of an age-set to cultural junior elder from Moran (Maasai for warrior age-set) at a manyatta or traditional homestead built specifically for the ceremony near Lemek town within the Masai-Mara National Reserve ecosystem in Narok county February 27, 2021. (Photo by Tony Karumba/AFP Photo)

A small section of the expanding remains of the Veil Nebula, a massive star that exploded about 8,000 years ago. The entire nebula is 110 light-years across, covering six full moons on the sky as seen from Earth, and resides about 2,100 light-years away in the constellation Cygnus, the Swan. (Photo by Reuters/NASA/ESA/Hubble)

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)