The National Geographic Photo Ark is a travelling exhibition of photographer Joel Sartore’s quest to create a photo archive of biodiversity around the world. So far, Sartore has captured studio portraits of more than 6,000 species – a number that he hopes to double. On 1 July, the ark will open at Melbourne zoo – the first time it has been exhibited in the southern hemisphere. More than 50 portraits will be on display, including many of Australian endangered animals being protected by programs at the zoo itself. These captions have been edited from text supplied by Melbourne zoo. Here: Barking owl. (Photo by Joel Sartore/National Geographic Photo Ark/The Guardian)

A British Museum representative poses for photographs next to Andy Warhol's “Mao”, left, and Jim Dine's “Drag: Johnson and Mao” which feature in “The American Dream: pop to the present” exhibition during a media photocall at the British Museum in London, Monday, March 6, 2017. The exhibition, which opens to the public from March 9 and runs until June 18, charts modern and contemporary print making. (Photo by Matt Dunham/AP Photo)

At the beginning of the 20th century, Edward S. Curtis set out to document what he saw as a disappearing race: the Native American. From 1907 to 1930, Curtis took more than 2,000 photos of 80 tribes stretching from the Great Plains to the Pacific Northwest and Alaska. He then published and sold these photos, along with narrative text, in 20 volumes of work known as “The North American Indian”. It is one of the most significant collections of its kind, “probably the most important photographic document of its age and its topic,” said Jeffrey Garrett, associate university librarian for Special Libraries at Northwestern University. (Photo by Edward S. Curtis)

Brave photographer Masa Ushioda captured the shots of this wild gator in vast marsh land in the Everglades National Park, in Florida, USA. He said: “Bright sunlight and blue sky were critical elements in this picture – in addition to getting a wild 10-foot alligator in the middle of the viewfinder with a perfect angle”.

Tank crew standing in front of M-4 tank, Ft. Knox, Kentucky, June, 1942. (Alfred Palmer/OWI/LOC)

A woman places her fingers into the crucifix-shaped holes in one of the ancient columns in the Church of the Nativity on December 22, 2011 in Bethlehem, West Bank. (Photo by Uriel Sinai/Getty Images)

Bikers are the knights of the modern times. They ride their steel horses; they drink and brawl and have their own strict code of honor. Some people view them as land-dwelling pirates; however, they are so much more than that. Photographer Sandro Miller is one of the few people who decided to look deeper than their rugged exterior, realizing that it takes more than a Harley Davidson bike and a leather jacket to make a biker. A true biker cannot be chained to a single place. The spirit of the true biker demands change, it seeks adventure, and it thirsts for freedom! (Photo by Sandro Miller)

A participant drives his 1960 Porsche 356 B as he arrives in Mexico City to take part in the Carrera Panamericana (“Pan-American Road Race”) in Mexico October 15, 2016. Participants from various countries take part in the seven-day race in Mexico. (Photo by Henry Romero/Reuters)