Khan, a five-year-old male White Bengal tiger, looks on inside an open-air cage at the Royev Ruchey zoo in Krasnoyarsk, Russia, October 21, 2016. (Photo by Ilya Naymushin/Reuters)

The top layer of muskeg and earth (L) is removed at the Syncrude tar sands operations near Fort McMurray, Alberta, September 17, 2014. Syncrude currently produces 350,000 barrels per day of high quality light, low sulphur crude oil according to company reports. (Photo by Todd Korol/Reuters)

A large bull walrus returns to the shores of Prins Karl Forland after diving and feeding on clams. (Photo by Paul Nicklen/National Geographic). Svalbard, Norway, 2011

A couple have taken their love of animals to the extreme – by opening up their home to over 100 rescued animals. Dr Prakash Amte and his wife, Dr. Mandakini Amte have dedicated their lives to helping both the animals – and people – of Hemalkasa, Maharashtra in India. Here: Prakash Amte is seen playing with a Hyena from his orphanage on September 19, 2017 in Maharashtra, India. (Photo by Haziq Qadri/Barcroft Media)

A midnight safari has been caught on camera as wild animals gather in front of a full moon. Photographer Brendon Cremer, 35, snapped the impressive collection of night sky images while in South Africa, Namibia, and Botswana. It can be challenging for even the best photographers to take full control of their camera while ensuring they don’t become the deadly animals' next meal. But this impressive set of images looks both effortless and fierce. Here: A elepant strolls under the milkyway. (Photo by Brendon Cremer/Caters News)

These snaps show a series of crafty critters camouflaged out of view. Many adventurous animals love to stand out from a crowd, but there are times when they need to blend in a bit more too. Photo: Tall story – can you spot the giraffe? (Photo by Caters News)

National Geographic photographer Steve Winter has spent most of his adult life shooting wild cats. Photo: A 14-month-old cub, cooling off in a pond, is riveted by a deer that appeared near the shore. Tigers are powerful swimmers; they can easily cross rivers four to five miles wide and have been known to swim distances of up to 18 miles. (Photo by Steve Winter/National Geographic)

Those lights are actually bioluminescent shrimp, better known as sea fireflies, or, in Japan, as “umibotaru”. Visible every year from May until the end of October, they live in the sand around very shallow sea water and are often seen floating between the extremes of high and low tides. Here: Bioluminescent sea fireflies glittering like diamonds on the rocks and sand. Okayama, Japan. July 2016. (Photo by Trevor Williams/Jonathan Galione/Getty Images)