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)

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)

Tactics reminiscent of the early American frontier days are now being used in Vietnam. Lieutenant Commander Donald D. Sheppard, UBN, of Coronado, California, aims a flaming arrow at a bamboo hut concealing a fortified Viet Cong bunker on the banks of the Bassac River, Vietnam on December 8, 1967. (Photo by AP Photo)

People participate in the first day of Thingyan Water Festival in Naypyitaw, Myanmar on April 13, 2018. The annual water festival, known as Thingyan, features large groups of people congregating to celebrate the by splashing water and throwing powder at each other's faces as a symbol of cleansing and washing away the sins from the old year. It marks the start of the traditional New Year and is similarly celebrated in countries such as Myanmar, Thailand, Laos and Cambodia. (Photo by Hein Htet/EPA/EFE/Rex Features/Shutterstock)

In this July 20, 2018 photo, Joshep Balta, a clown named “Cachupito”, peers through the tent curtain to see how many people are waiting for the show, put on by the International Circus, set up in the shanty town of Puente Piedra on the outskirts of Lima, Peru. Balta, a 12-year old clown whose parents work at the circus setting up and breaking down the encampment, was discovered by the circus two years ago when he was performing as a clown at street corners. (Photo by Martin Mejia/AP Photo)

Model Daisy Lowe has been camouflaged into a wall of daisies by world-leading body paint artist Carolyn Roper, to showcase the Samsung QLED TV's Ambient Mode feature in London, United Kingdom on August 2, 2018. The work took eight hours to complete. (Photo by Matt Alexander/PA Wire)

Wigan Town center came alive with Hundreds of Revellers dressing up in fancy dress on December 26, 2018. Revellers in fancy dress braved the cold weather in Wigan, a town in Greater Manchester, England for the town's strangest holiday tradition – the Boxing Day dress up. (Photo by Dave Nelson/The Sun)

This handout picture taken on December 13, 2016 and released on December 14, 2016 by the Tiergarten Schoenbrunn zoo in Vienna, Austria, shows a baby sloth eating some salad as it hangs on it's mother's belly in their enclosure. The baby was born already on November 18, 2016, but according to the zoo it could be picured for the first time only now as it usually hides in it's mother's soft coat. (Photo by Daniel Zupanc/AFP Photo)