“Slow”. A calm cow in the messy streets of Jodhpur. Photo location: India. (Photo and caption by Matthias Troeger/National Geographic Photo Contest)

“7584 Fish”. On a windy day right after a Cyclone passed the far northern Great Barrier Reef i took some friends out to the reef. Never before i saw that many glass fish on this particular coral “bommie”. Just when i setup my camera, this Napoleon Wrasse swam right through the school of fish building a living frame. Photo location: Cairns, Great Barrier Reef, Flynn Reef, Australia. (Photo and caption by Christian Miller/National Geographic Photo Contest)

An officer of the Afghan border police throws an assault rifle to a policeman participating in a military exercise on the outskirts of Herat, Afghanistan, Monday, September 7, 2015. Twelve female and seventy male border police personnel participated in the military exercise near the border with Iran in Herat province. (Photo by Hoshang Hashimi/AP Photo)

Members of a teenage girl gang convincing an unwilling recruit to join the gang, circa 1955. (Photo by Vecchio/Three Lions)

A view of the spectacular colour of clouds at sunset on January 17, 2005 in Beijing, China. (Photo by China Photos/Getty Images)

A landscape photographer turned the camera on himself to take a set of incredible selfie while visiting some of the world's most beautiful destinations. Paul Zizka, 39, from Alberta, Canada, has been a photographer for nine years, and thought that featuring in his own pictures would emphasize the nature surrounding him and create a more unique shot. Here: Lake Minnewanka, Banff National Park, Alberta, Canada. (Photo by Paul Zizka/Caters News Agency)

In this Monday, September 22, 2014 photo provided by the Utah Division of Wildlife Resources, a young cougar is released back into Utah's mountains by the Utah Division of Wildlife Resources in an undisclosed site in central Utah. State wildlife officials received reports of the cougar roaming Sunday afternoon in a residential area of the city's eastern flank, a few miles from the base of the Wasatch Mountains. Authorities say cougars generally avoid humans but sometimes enter neighborhoods close to their mountain habitats. (Photo by Steve Gray/AP Photo/Utah Division of Wildlife Resources)

A pigeon rests on a wild iguana in a tree inside Seminario Park in Guayaquil, Ecuador, Thursday, April 3, 2014. Pigeons coexist with the wild iguanas at this park in the middle of the city surrounded by savannah. (Photo by Dolores Ochoa/AP Photo)