British artist, Mark Coreth sits on top of the “Sydney Ice Bear” carved from a 10 tonne block of ice to illustrate how humans affect climate change in the Arctic at Customs House on June 3, 2011 in Sydney, Australia. The public will be welcomed to touch the bear, and leave an imprint which will begin the melting process and act as a metaphor for how humans affect the environment. The ice bear's has visited six cities on it's global tour since 2009; the visit to Sydney coincides with World Environment Day on June 5. (Photo by Lisa Maree Williams/Getty Images)

A leopard seal feeds Paul Nicklen a penguin. (Photo by Paul Nicklen/National Geographic). Antarctic Peninsula, 2011

The sea leopard. The Antarctic Peninsula. (Photo by Paul Nicklen)

It's not often that two ferocious tigers have to beat a hasty retreat from a confrontation. But it seems that the wrath of a mother bear protecting two cubs on her back was more than enough to scare this pair off. Wildlife photographer Aditya Singh captured the encounter during a visit to Ranthambore Tiger Reserve in Rajasthan, India.

Cynthia the Kodiak Bear enjoys a whole Tasmanian Atlantic Salmon to celebrate her 28th birthday at Taronga Zoo on January 17, 2005 in Sydney, Australia. (Photo by Matt King/Getty Images)

Australian photographer Brendan Fitzpatrick’s X-ray photographs expose the inner workings of toys. Fitzpatrick’s photographs are both whimsical and mechanical, evoking the curiosity of childhood and the desire to discover how things look and work from other perspectives. The strategic placement of wires, batteries, and screws are revealed, the complexity of the inside contrasting with the seemingly simplistic design of the outside. Fitzpatrick uses chest X-ray and mammogram machines to photograph flowers, toys, and creatures, then enhances the color in the images in order to more effectively distinguish the various parts that have been exposed. This photographs are part of series he calls “Invisible Light”. (Photo by Brendan Fitzpatrick)