Juan Manuel Borrero / Casa Batllo, a building by architect Antoni Gaudi, Sant Eixample District, Barcelona City, Spain, March 2011

Juan Manuel Borrero / The roof of Casa Batllo, a modernist building by Antoni Gaudi, Eixample District, Barcelona City, Spain, July 2010

Erlend Haarberg / Curved layers of marble and calcium-silicate flowing around mica schist from the Engabreen Glacier, Saltfjellet-Svartisen National Park, Nordland, Norway, September 2006

Hiroya Minakuchi / Orca (Orcinus orca) male with curved dorsal fin, Shiretoko, Hokkaido, Japan

Andrew Parkinson / Mute swan (Cygnus olor) abstract view of neck as it feeds, Derbyshire, UK, April.

Kristel Richard / Close up of small curved ears of Kathiawari stallion, Inaj National Stud, Gujarat, India, January 2011

Edwin Giesbers / Common Coot (Fulica atra) swimming and leaving a curved wake. The Netherlands, July.

Kristel Richard / Two rare Kathiawari mares and a stallion (on the left) stand attentive with their ears curved, in Jasdan, Gujarat, India. 2010

Kristel Richard / Close up of the curved ears of a rare Cremello Kathiawari mare, in Jasdan, Gujarat, India. 2010

Chien Lee / Curved Spiny Spider (Gasteracantha arcuata) showing unusual tubercles with unknown function, Lambir Hills National Park, Borneo, Malaysia

Chien Lee / Curved Spiny Spider (Gasteracantha arcuata) with unusual tubercles with unknown function, Lambir Hills National Park, Borneo, Malaysia

Kristel Richard / Close up of the curved ears of a grey Marwari mare in traditional colourful bridle, Bhavnagar, Gujarat, India, 2008