Swedish brown bears “Fred” and “Frode” play in the snow on January 30, 2014 at the Natur- und Umweltpark (NUP) animal park in Guestrow, northeastern Germany. Despite of icy temperatures, the bear brothers took a break from their winter rest. (Photo by Bernd Wuestneck/AFP Photo/DPA)

From the 1940s through the 1960s, the Alfred Mainzer Company of Long Island City, NY published a series of linen and photochrome humorous cat postcards illustrated by Eugen Hartung (or Hurtong) (1897–1973), sometimes referred to as “Mainzer Cats”. These postcards normally illustrate settings that are filled with action, often with a minor disaster just about to occur. While the dressed cats were by far the most popular and most plentiful cards, Hartung also painted other dressed animals – primarily mice, dogs, and hedgehogs.

This photo was caught on camera by amateur photographer Kutub Uddin, 27, and was taken in his back garden in Bognor Regis, West Sussex. The red-eyed tree frogs have been Mr Uddin's pets for four months and he often lets them out to roam around his garden. Photo: “Ohh no :( Raining”. (Photo by Kutub Uddin)

The pygmy marmoset (Cebuella pygmaea) is a small New World monkey native to rainforests of the western Amazon Basin in South America. It is notable for being the smallest monkey in the world at just over 100 grams (3.5 oz). It is generally found in evergreen and river edge forests and is a gum-feeding specialist

These beautiful photos capture the tender moments between two young boys who share a unique bond with animals. Elena Shumilova, from Andreapol, Russia, began taking pictures of her sons Yaroslav and Vanya in early 2012 when she received her first professional camera. The pair were immediately accepted by the animals from a young age and their incredible bond continues to strengthen as they get older. Elena, 32, was able to capture images her boys playing with such animals as rabbits, dogs, cats and ducks as they become totally immersed in their communication with their furry friends. (Photo by Elena Shumilova)

“The Tasmanian devil (Sarcophilus harrisii) is a carnivorous marsupial of the family Dasyuridae now found in the wild only in the Australian island state of Tasmania. The size of a small dog, it became the largest carnivorous marsupial in the world following the extinction of the thylacine in 1936. It is characterised by its stocky and muscular build, black fur, pungent odour, extremely loud and disturbing screech, keen sense of smell, and ferocity when feeding”. – Wikipedia. Photo: A Tasmanian Devil bears it's teeth at a quarantine facility August 31, 2005 in Hobart, Australia. (Photo by Ian Waldie/Getty Images)

A frog sits on a leaf and instead of seeing a reflection of itself in the water below, it sees a snail, attached to the bottom of the leaf, in a fish tank in Vietnam. (Photo by Duong Quoc Dinh/Solent Ne/SIPA Press)

The sea otter (Enhydra lutris) is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between 14 and 45 kg (31 and 99 lb), making them the heaviest members of the weasel family, but among the smallest marine mammals. Unlike most marine mammals, the sea otter's primary form of insulation is an exceptionally thick coat of fur, the densest in the animal kingdom. Although it can walk on land, the sea otter lives mostly in the ocean.