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)

Clinging on with sticky toes, a green tree frog sits bravely on its unlikely friend – a large tree python. Curled around the branches of a small coconut tree, the snake appears relatively undisturbed by the bold passenger that has clambered onto its skin. Grown in captivity together, the pair display no signs of aggression or fear, comfortable with their encounters high up in the leafy branches. Photo enthusiast Fahmi Bhs watched in surprise as the frog slowly climbed along the scales of the metre long snake in a zoo in Jakarta, Indonesia. (Photo by Fahmi Bhs/Solent News/SIPA Press)

Russian policemen detain a participant taking part in an unauthorized protest against Russia's partial military mobilization due to the conflict in Ukraine, in downtown of Moscow, Russia, 24 September 2022. Russian President Putin announced in a televised address to the nation on 21 September, that he signed a decree on partial mobilization in the Russian Federation. Russian citizens who are in the reserve will be called up for military service. On 24 February 2022 Russian troops entered the Ukrainian territory in what the Russian president declared a “Special Military Operation”, starting an armed conflict that has provoked destruction and a humanitarian crisis. (Photo by Maxim Shipenkov/EPA/EFE)

Russian policemen detain a person taking part in an unauthorized protest against Russia's partial military mobilization due to the conflict in Ukraine, in downtown Moscow, Russia on 24 September 2022. Russian President Putin announced in a televised address to the nation on 21 September, that he signed a decree on partial mobilization in the Russian Federation. Russian citizens who are in the reserve will be called up for military service. On 24 February 2022 Russian troops entered the Ukrainian territory in what the Russian president declared a “Special Military Operation”, starting an armed conflict that has provoked destruction and a humanitarian crisis. (Photo by Maxim Shipenkov/EPA/EFE)

Policemen guard Poland's Supreme Court as a protester lies on the pavement in Warsaw, Poland, on Thursday, April 22, 2021. A disputed disciplinary body within Poland's Supreme Court is examining a motion that could result in the arrest of a judge who has become a symbol of the fight for an independent judiciary. (Photo by Czarek Sokolowski/AP Photo)

An Olympic Airways airplane stands on the premises of the former Athens International airport, Hellenikon June 16, 2014. For about six decades Hellenikon was Athens' only airport but it closed down in 2001 to make way for a newer, more modern airport before the city hosted the 2004 Olympic Games. After languishing for years as a wasteland of crumbling terminals, Hellenikon is set for resurrection as a glitzy coastal resort. Lamda Development, controlled by Greece's powerful Latsis family and leading a consortium of Chinese and Abu-Dhabi based companies, has big dreams for the area since signing a 915 million euro deal for a 99-year lease in March 2014. (Photo by Yorgos Karahalis/Reuters)

In 2002 photographer Corey Arnold left behind a poor economy in San Francisco and headed up to Alaska to try his luck at his longtime passion of fishing. Arnold, who had worked summers during college on a salmon boat in Alaska, signed onto the f/v Rollo, a crabbing boat that fishes in the dangerous Bering Sea. While working long, strenuous hours on the Rollo, Arnold often stole away with the captain’s permission to grab his camera and photograph the crew and the ship. Arnold eventually put together “Fish Work: Bering Sea”, a documentation of his seven adventurous and dicey crab seasons aboard the Rollo. (Photo by Corey Arnold)