The photographs feature fish that have been specially treated to make the stained skeletal tissues visible through the skin and flesh. The technique, developed by Dr. Adam Summers, uses dyes, hydrogen peroxide, a digestive enzyme and glycerin to make the flesh seem to disappear. Photo: This image of the butterfly ray (Gymnura crebripunctata) helped scientists study the joints in its wings. (Photo by Adam Summers)

“About nine years ago Photographer Bob Carey and his wife, Linda moved to America's East Coast. Even though the move was exciting, exhilarating, and inspiring, it was a big and dramatic change. The self portraits were a perfect way of expressing himself. He posed in different surroundings wearing a pink tutu. The result is a wonderful, inspiring and poetic series of self portraits: The Tutu Project” – Michael Werner. (Photo by Bob Carey via TheTutuProject.com)

A woman looks at photographs of dogs to choose a pet to rent at Puppy The World on January 24, 2009 in Tokyo, Japan. Rent-a-dog is becoming increasingly popular amongst people who love dogs but are unable to look after a pet full time due to limited living space or long working hours. Customers pay the dog-rental outlet around 2500 yen (32.5 USD) for an hour, and usually take their rented pet for a walk along the nearby beach. (Photo by Junko Kimura/Getty Images)

“These stunning ultra-high speed photos of water droplets were captured by photographer, Ronny Tertnes, 48, from Bergen, Norway. They show the water’s displacement as various liquids are being dropped in. Ronny, who works full time as an IT administrator, set up his camera and flash rigs to capture the exact moment a droplet hit the surface, sometimes causing several drops to collide into each other”. – TwoByTwoEditorial.co.uk. (Photo by Ronny Tertnes/TwoByTwoEditorial.co.uk)

Japan is a country full of art. Much of this is housed in museums and galleries, but others are right under our feet. We speak, of Japan’s peculiar obsession with manhole covers. Almost anywhere in the country you can find manhole covers with spectacular grounds, each more beautiful and complex than the previous. In recent years, S. Morita photographer has traveled around Japan and leave us this great gathering on the beautiful and artistic Japanese manhole covers.

With more than 40,000 followers on Twitter and 26,400 fans on Vine, it looks like Marutaro the hedgehog from Japan is one of the most popular hedgehogs on the Internet. And as his owner keeps on posting Marutaro’s pictures online daily, Marutaro’s popularity continues to grow. There are hundreds of cute photographs and videos of this little fellow, but the ones with little paper cut-out faces are probably the cutest. As Marutaro lies on his back, his owner gives him a variety of silly expressions and smiles. The 20 best of them will definitely boost your mood!