Eric Stohr from Cardiff Metropolitan University carries out an ultrasound scan on Bali, a 7 metre (23 feet) long reticulated Python snake at Chester Zoo in Chester, northern England September 5, 2012. The zoo's two reticulated pythons are taking part in cardiological study as part of a joint research programme between the zoo and Cardiff Metroploitan University. REUTERS/Phil Noble (BRITAIN - Tags: SCIENCE TECHNOLOGY ENVIRONMENT ANIMALS HEALTH)