The world’s biggest snake resides in the Amazon, and with the largest predators being one of the best indicators of the condition of an environment, a single scale from the giant green anaconda has the ability to reveal the health of the entire ecosystem. What is a dream and thrilling prospect for Professor Bryan Fry is a daunting reality for @WillSmith. Watch Pole to Pole with Will Smith, Wednesdays at 8pm on National Geographic UK Also streaming on Disney | National Geographic UK

Hercules, one of our Reticulated Pythons (Malayopython reticulatus), looking good afternoon shed. This is the longest species of snake in the world where Green Anacondas are the heaviest. Originating from South East Asian this is the only species that has been recorded swallowing grown men whole. The record length was around 10 to 11m, which is a massive snake. We don't see the giant record breakers anymore as people have killed the giant genes due to the skin and meat trade. This is a very dang