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)

American actress Paris Jackson pulls faces at photographers during the “Melbourne Cup” race day festivities in Melbourne, Australia on November 7, 2017. (Photo by Media-Mode/Splash News and Pictures)

Rescuers attempt attempt to push stranded whales back into the ocean at Ujong Kareng beach in Aceh province, Indonesia, Monday, November 13, 2017. An official said a small pod of whales was stranded at the beach and attracted hundreds of onlookers who posed for pictures with them. (Photo by AP Photo/Zulkarnaini)

Bella Hadid arriving at her hotel on December 7, 2017 in London, England. (Photo by Palace Lee/PacificCoastNews)

The moon rises behind the skyline and financial district in Toronto, November 25, 2015. (Photo by Mark Blinch/Reuters)

A woman walks past a caricature of Britain's Foreign Secretary Boris Johnson in east London, Britain November 18, 2016. (Photo by Andrew Winning/Reuters)

Pascal Craymer seen attending Pam Hogg at Freemason's Hall during LFW February 2018 on February 16, 2018 in London, England. (Photo by Goff Photos)

Model Abbey Clancy attends The BRIT Awards 2018 held at The O2 Arena on February 21, 2018 in London, England. (Photo by MagicMoments UK)