Macaques huddle together for warmth at a hot spring in Nagano, Japan in the last decade of December 2023. Known as snow monkeys, the animals soak in the 40°C water every day during cold weather, spending their bathtime grooming, snoozing and playing on visitors’ camera tripods. (Photo by David Lazar/Animal News Agency)

Teenagers playing with mud started the Bloco da Lama in 1986 and it has since become an annual event in the city of Paraty, Brazil. Hundreds of people wrestle, coat each other in mud and throw it around to the sound of samba and reggaeton at a carnival beach party on February 18, 2023. Clothes are optional, but mud is not. (Photo by Fabio Teixeira/SIPA Press/Profimedia)

Tourists play at a beach covered by a thick layer of green algae on July 3, 2013 in Qingdao, China. A large quantity of non-poisonous green seaweed, enteromorpha prolifera, hit the Qingdao coast in recent days. More than 20,000 tons of such seaweed has been removed from the city's beaches. (Photo by China Foto Press)

Honourable mention, Behaviour category. Toss the scorpion – Indian roller playing with its kill by Susmita Datta. The image was taken during an early morning safari drive at Tadoba Andhari Tiger Reserve in India. (Photo by Susmita Datta/PA Wire/Royal Society Publishing Photography Competition 2017)

A Hawaiian cleaner wrasse provides its cleaning services to a yellowfin goatfish in a reef community off the Big Island in Hawaii. Cleaner species help rid their hosts of ectoparasites, dead tissue, bacteria and fungi. Studies have shown cleaning to play a vital role in keeping many reef ecosystems healthy. (Photo by Marty Snyderman/Caters News Agency)

Indian students play with coloured powders as they celebrate “holi” or the “festival of colours” during a special function in Kolkata on March 12, 2017. Holi, the popular Hindu spring festival of colours, is observed in India at the end of the winter season on the last full moon of the lunar month, and will be celebrated on March 13 this year. (Photo by Dibyangshu Sarkar/AFP Photo)

Canberra resident Bruce Gibbons is seen surrounded by grazing kangaroos as he plays a shot during a session on a practice fairway at Gold Creek Golf Club in Canberra, Australia, May 16, 2017. (Photo by Lukas Coch/Reuters/AAP)

Frogs playing dominos at the Frog Museum, a collection of 108 stuffed frogs in scenes portraying everyday life in the 19th-century and made by Francois Perrier, in Estavayer-le-Lac, Switzerland on November 7, 2018. (Photo by Denis Balibouse/Reuters)