Children play football in front of an abandoned train compartment next to a railway track in Dhaka, in this May 29, 2014 file photo. (Photo by Andrew Biraj/Reuters)

A pile of destroyed cars of teachers sits outside Briarwood elementary school in Oklahoma City, Oklahoma May 22, 2013. Rescue workers with sniffer dogs picked through the ruins on Wednesday to ensure no survivors remained buried after a deadly tornado left thousands homeless and trying to salvage what was left of their belongings. Curvature of horizon in the photo is due to an ultra-wide angle lens. (Photo by Rick Wilking/Reuters)

Three very colouful alpacas enjoy the hot weather at Toft Farm, Rugby, on July 19, 2013. (Photo by Caters News)

In this Wednesday, May 23, 2012 photograph, a young deer and a cat share a moment in Feench village near Jodhpur, Rajasthan state, India. (Photo by AP Photo)

A large Pacific sideband snail slowly crosses a rain wet road in rural Douglas County, Oregon near Elkton on Sunday, December 2, 2012. The moisture loving snail should be very content with the recent heavy rains in southwestern Oregon and northern California. (Photo by Robin Loznak)

Gorillas at Royal Burgers’ Zoo, Arnhem, Netherlands, on November 28, 2013. (Photo by Vidi Photo/Startraks Photo New York)

Jack, a Lurcher from Dogs Trust Salisbury, walks past a window display of models in a Dogs Trust shop window in Salisbury, as part of a campaign to discourage the impulse buying of dogs ahead of Valentine's Day, on February 10, 2014. (Photo by Matt Alexander/PA Wire)

A three-month-old Sumatran tiger cub named “Bandar” shows his displeasure after being dunked in the tiger exhibit moat for a swim reliability test at the National Zoo in Washington, on November 6, 2013. All cubs born at the zoo must take a swim test before being allowed to roam in the exhibit. Bandar passed his test. (Photo by Manuel Balce Ceneta/Associated Press)