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)

A contestant lies in a chili covered pool eating Chillies during a chili eating contest on July 8, 2018 in Ningxiang, Hunan Province of China. Citizen Tang Shuaihui ate 50 Chillies in one minute winning the contest. (Photo by VCG/Getty Images)

Iraqi teenagers swim in waste water from the nearby Tuweitha nuclear facility near Baghdad, Iraq on May 28, 2003. Iraqis are consuming contaminated water unaware of the dangerous pollutants that can cause severe ill health. (Photo by Damir Sagolj/Reuters)

Tigray refugees who fled the conflict in the Ethiopia's Tigray arrive with their donkey on the banks of the Tekeze River on the Sudan-Ethiopia border, in Hamdayet, eastern Sudan, Saturday, November 21, 2020. (Photo by Nariman El-Mofty/AP Photo)

A local wears a plastic water bottle with a cutout to cover her face, as she walks on a footbridge in Hong Kong on January 31, 2020, as a preventative measure following a virus outbreak which began in the Chinese city of Wuhan. The World Health Organization, which initially downplayed the severity of a disease that has now killed 170 nationwide, warned all governments to be “on alert” as it weighed whether to declare a global health emergency. (Photo by Anthony Wallace/AFP Photo)

The May Queen during the Beltane Fire Festival in Edinburgh, Scotland on April 30, 2022. A dynamic reinterpretation of an ancient Celtic celebration of the return of summer, the festival is centered around the story of the May Queen and the Green Man, and the lighting of the Beltane bonfire, symbolic of purification, healing and new life. Edinburgh's Beltane celebrations are the largest of their kind in the world with around 250 volunteer performers and thousands of spectators. (Photo by Jane Barlow/PA Images via Getty Images)

Indian army training cadets perform “Kalaripayattu”, an ancient martial art from Kerala, during a combined display ahead of their graduation ceremony, at the Officers Training Academy (OTA), in Chennai, India on September 8, 2023. A combined display of training proficiency was organized at the OTA as a prelude to a passing-out parade of cadets. The combined display marks the culmination of the adventure training and showcases the skills and expertise of armed forces display teams. (Photo by Idrees Mohammed/EPA/EFE)

A student walks past on the broken bridge hit by a river overflow following floods in Jaranih village, Central Hulu Sungai, South Kalimantan province, Indonesia on November 17, 2021. (Photo by Bayu Pratama S./Antara Foto via Reuters)