Women wearing traditional hats, known as a non la, sell fruits in Hoi An, Vietnam April 4, 2016. The non la hats are made of readily available materials such as palm leaves, tree bark and bamboo and are visible everywhere in the city, a UNESCO World Heritage site. Hoi An's history as a busy trading port is evident throughout its architecture, a mix of eras and styles, with traditional wooden Vietnamese houses, Chinese temples and French colonial buildings. (Photo by Jorge Silva/Reuters)

Workers hold an 80 Kg Paiche (Arapaima gigas) to return it to a pool at a breeding farm in Nueva Loja, Ecuador, March 25, 2016. (Photo by Guillermo Granja/Reuters)

A worker is immersed in a kaleidoscope of colour while they paint traditional umbrellas in Juwiring, Klaten, Central Java, Indonesia in December 2023. The workers who spend around 8 hours a day, depending on order quantities and customer deadlines are paid around Ј200 a month. They will paint a batch over the period of two to three days until each layer of paint is dry. Extras of the traditional umbrella will be made as many tourists come to buy them. (Photo by Lia Indriani/Solent News & Photo Agency)

In this Thursday, June 14, 2018, file photo, students wear virtual reality goggles during a science class at Pyongyang Teachers' University, a teacher training college, in Pyongyang, North Korea. (Photo by Dita Alangkara/AP Photo)

A kingfisher dives into the leafy water of the River Alde near Rendham, Suffolk in the second decade of November 2022 and catches two fish. Kingfishers must be able to see the fish they want to catch before making their dive, so for this bird to be successful when leaves covered the surface of the water shows its true skill for survival. (Photo by Ivor Ottley/Animal News Agency)

A police officer from an explosive disposal unit takes part in a security drill ahead of next year's general election in Sidoarjo, East Java, on August 23, 2023. (Photo by Juni Kriswanto/AFP Photo)

A police officer stands at a police cordon near the scene of a terror attack in London, U.K., on Sunday, June 4, 2017. A van swerved into Saturday-night crowds on London Bridge, before three men got out and went on a stabbing rampage through nearby bars. (Photo by Luke MacGregor/Bloomberg)

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)