Five lions: 'the best nature photographs of all time'

Hauled out on the rocks, they may look plump and ungainly, but under the surface, sea lions are all grace and elegance, as this photograph of some playing in the sea grass beds off Little Hopkins Island, South Australia, clearly shows.

The photograph has been selected by the International League of Conservation Photographers for its "top 40 nature photographs of all time" collection. The pictures, many of which will be on sale as part of Christie's "Green Auction" to mark Earth Day today, include images of a polar bear swimming submerged with its image reflected in the icy water, giant tortoises gathered at dawn in the Galapagos Islands and a thresher shark caught in a fishing net. It will also include an image of the Earth viewed from space over the moon's horizon, and a picture of a chimpanzee reaching out its hand to conservationist Jane Goodall. Funds raised at the New York auction will go to four conservation groups – Conservation International, Oceana, the Natural Resources Defence Council and the Central Park Conservancy.

Click here or on the image to see other examples from the collection