Mr. Ben, a pygmy slow loris, is administed anesthetic during one of Bristol Zoo's in-house veterinary clinic routine health check-up and teeth clean as part of the Zoo's standard animal husbandry and welfare procedure at Bristol Zoo on June 18, 2009 in Bristol, England. (Photo by Matt Cardy/Getty Images)

Koreans spin fire cans during “Jwibulnoli” a South Korean folk game at Han River on February 5, 2012 in Seoul, South Korea. The event is part of a “Daeboreum”, a Korean holiday that celebrates the first full moon of the lunar new year. (Photo by Chung Sung-Jun/Getty Images)

A plane passes the Full moon as it rises over Albert Bridge on February 7, 2012 in London, England. Albert Bridge is said to be one of the most romantic bridges in London, and will be the start point for the flotilla of boats that will make their way along the Thames as part of the Queen's Diamond Jubilee celebration. (Photo by Dan Kitwood/Getty Images)

People pray inside a temple at the Janmashtami Hindu Festival at Bhaktivedanta Manor on August 22, 2011 in Watford, England. Up to 72,000 were expected to take part in the two day festival celebrating the birth of Krishna, in what is believed to be the largest Hindu festival gathering outside of India. (Photo by Dan Kitwood/Getty Images)

Girls of the Long Horn Miao ethnic minority group wear headdresses as they prepare gather for Tiaohua or Flower Festival as part of the Lunar New Year on February 6, 2017 in Longga village, Guizhou province, southern China. (Photo by Kevin Frayer/Getty Images)

In this Thursday, December 1, 2016 photo, Cat Bigney, part of the Oglala Native American tribe, waits on the shore of the Cannonball river for travelers to arrive by canoe at the Oceti Sakowin camp where people have gathered to protest the Dakota Access oil pipeline in Cannon Ball, N.D. So far, those at the camp have shrugged off the heavy snow, icy winds and frigid temperatures. But if they defy next week's government deadline to abandon the camp, demonstrators know the real deep freeze lies ahead. Life-threatening wind chills and towering snow drifts could mean the greatest challenge is simple survival. (Photo by David Goldman/AP Photo)

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)

People take part in a sunset ceremony on the lower slopes of Glastonbury Tor as they celebrate Samhain at the Glastonbury Dragons Samhain Wild Hunt 2017 in Glastonbury on November 4, 2017 in Somerset, England. To celebrate Samhain, the Glastonbury Dragons, alongside Gwythyr Ap Greidal, the Summer King and the Winter King, (Photo by Matt Cardy/Getty Images)