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)

Filipino children play as they are doing caroling activities on the street near an airport, days before Christmas in Manila, Philippines, 20 December 2017. Filipinos celebrate the longest Christmas in the world which starts as early as September every year. (Photo by Francis R. Malasig/EPA/EFE)

Women dancing at the disco club Xenon in New York City, USA in 1978. Xenon was a popular disco in Manhattan in the late 1970s and early 1980s. It was the only nightclub popular enough to compete with Studio 54. (Photo by Waring Abbott/Getty Images)

A hint of Spring Fever is evidenced by this passerby tipping his hat to a store fixture mannequin on a State St. sidewalk in downtown Chicago on March 23, 1978. The mannequin was awaiting pickup to be transported. (Photo by AP Photo)

Iraqi government forces are seen near the Falahat village west of Fallujah on June 27, 2016. Iraqi forces took the Islamic State group's last positions in the city of Fallujah on June 26, establishing full control over one of the jihadists' most emblematic bastions after a month-long operation. (Photo by Moadh Al-Dulaimi/AFP Photo)

2016 Rio Olympics, Gymnastics training, Rio Olympic Arena, Rio de Janeiro, Brazil on August 4, 2016. Close up of the feet of Rebecca Downie (GBR) of United Kingdom as she trains on the beam. (Photo by Dylan Martinez/Reuters)

One of the largest paddle steamers afloat in Britain is the H.M.S. Royal Eagle, former peacetime excursion boat which carried passengers on pleasure jaunts from Tower Bridge to Southend, Ramscate and Margate. Commissioned two years ago as a warship of the Royal Navy, the craft has been in action 52 times against enemy aircraft. The Eagle took part in the evacuation from Dunkirk where she was dive-bombed 48 times and brought home nearly 3,000 British troops. Members of the crew cleaning the paddle boxes of H.M.S. Royal Eagle in London on January 18, 1943. (Photo by AP Photo)

A woman smokes marijuana during a Global March for Marijuana in Medellin, Colombia, May 5, 2018. The annual Global Marijuana March is taking place in over 100 cities across the world in an effort to raise awareness of the benefits of medical cannabis and to call for the legalization of marijuana. (Photo by Fredy Builes/Reuters)