Charlene Wittstock (L) and Prince Albert II of Monaco (R) attend the singles Final match between Rafael Nadal of Spain and Roger Federer of Switzerland on day nine of the Monte Carlo Masters Series tennis tournament. (Photo by Pascal Le Segretain/Getty Images). 2008

A novice Bhutanese monk sleeps after hours of prayer waiting for class to be over at the Dechen Phodrang monastery October 18, 2011 in Thimphu, Bhutan. The monks average about 10 hours of study a day waking up at 5:00am. (Photo by Paula Bronstein/Getty Images)

People purchase the book “Steve Jobs” by Walter Isaacson on launch day at Shanghai's City of Books on October 24, 2011 in Shanghai, China. The book was launched in 30 book cities at the same time across the country. (Photo by ChinaFotoPress/Getty Images)

A baby hippopotamus lies next to its mother on the first day it was presented to the public at the Zoo Berlin zoo on November 1, 2011 in Berlin, Germany. The baby hippo was born at the zoo on October 23. (Photo by Sean Gallup/Getty Images)

Wildlife are hunted down for consumption or for sale in the India eastern state of Nagaland. Hunters can make a good living, with some bred for food or to be sold as pets. These baby parrots, photographed by Caisii Mao via Sipa USA, are seen after they were caught and preserved by a local hunter and for sale at a private residence in Dimapur, India north eastern state of Nagaland on Wednesday, July 24, 2013. (Photo by Caisii Mao/NurPhoto/Sipa USA)

The Solar Impulse 2 airplane, flown by test pilot Markus Scherdel, flies off the coast of Oahu during a test flight from Kalaealoa Airfield in Kapolei, Hawaii, March 3, 2016. The solar-powered plane is ready to continue its revolutionary voyage around the world. After the craft was grounded in Hawaii last July due to overheated batteries, it was repaired and upgraded, and a recent initial test flight proved successful. (Photo by Eugene Tanner/Reuters)

Members of the association historical recreation Frente del Nalon participate in the recreation of the battle: “The Siege of Oviedo” that took place during the Spanish Civil War, in Grullos, near Oviedo, in northern Spain, September 3, 2016. The Siege of Oviedo lasted from July 19 until October 16, 1936. The town garrison, under the command of Colonel Antonio Aranda Mata, declared for the uprising and held out until relieved by a Nationalist force. (Photo by Eloy Alonso/Reuters)

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)