Coloured X-ray of a barn owl. A physicist has used X-ray to create an extraordinary collection of artwork. Arie van't Riets pictures reveal birds, fish, monkeys and flowers in an incredible new light. The 66-year-old, from Bathmen in the Netherlands, began X-raying flowers as a means to teach radiographers and physicians how the machine worked. But after adding a bit of colour to the pictures, the retired medical physicist realised the potential for an exciting new collection of art. (Photo by Arie van't Riet/Barcroft Media)

A adorable bear cub cant get enough of playing buckaroo – as it hangs onto its mum splashing about in a river. His mum was attempting to catch a fish supper for the pair as the plucky cub continued to jump on her back. And as she was concentrating on her meal the young bear became a distraction. So she sprung into life with him on her back before he was tossed into the water much to his delight. (Photo by Lisa Sidorsky/Caters News)

A monarch butterfly rests on a visitor's hand at the Monarch Grove Sanctuary in Pacific Grove, California December 30, 2014. Monarch butterflies may warrant U.S. Endangered Species Act protection because of farm-related habitat loss blamed for sharp declines in cross-country migrations of the orange-and-black insects, the U.S. Fish and Wildlife Service said. (Photo by Michael Fiala/Reuters)

A visitor celebrates after attending a bare hand fishing event in a frozen river during the Hwacheon Sancheoneo Ice Festival at Hwacheon-gun, Gangwon province, South Korea, 09 January 2016. The festival runs under the theme “Unfrozen Hearts, Unforgettable Memories” from 09 January to 31 January 2016. (Photo by Jeon Heon-Kyun/EPA)

The fourth annual BigPicture Natural World Photography Competition aims to celebrate the diversity of life on Earth, and encourages people to protect and conserve it. Here: “The Salmon Catchers”. Terrestrial Wildlife. To capture this view of a mother grizzly bear and her cub, photographer Peter Mather set up a camera trap on a log that he knew the bears tended to traverse while fishing for salmon, in the Yukon River watershed in Canada. (Photo by Peter Mather/BigPicture Natural World Photography Competition 2017)

A Humboldt penguin swims in a pool during the annual stock take at ZSL London Zoo in London, Thursday, January 2, 2020. Caring for more than 500 different species, ZSL London Zoo's keepers face the challenging task of tallying up every animal large and small, every mammal, bird, reptile, fish and invertebrate at the Zoo. (Photo by Frank Augstein/AP Photo)

Filipino children play at a fishing village along the coast of Manila Bay, Philippines, 30 May 2023. As a precaution of approaching Typhoon Mawar, Philippine government authorities have evacuated thousands of residents, imposed a no-sail ban, suspended school classes, and shutdown offices in the northern part of Luzon island, the country's largest and most populous island. (Photo by Francis R. Malasig/EPA/EFE/Rex Features/Shutterstock)

A cat sits underneath lanterns displayed at Tai O fishing village on September 07, 2022 in Hong Kong, China. Hong Kong prepares ahead to celebrate the mid-autumn festival which is an occasion for a children's night out and family gathering with the customs of moon contemplating, a procession of star and moon-shaped lanterns, lion dance, as well as holding parties with moon cakes and fruits. (Photo by Anthony Kwan/Getty Images)