Planet Earth II gives viewers nightmares with 'terrifying' snakes

There was a lonely sloth and fighting komodo dragons when David Attenborough returned to BBC1 with Planet Earth II last night, but it was a group of killer snakes the biggest impression on viewers.

Wildlife fans watched happily as newly hatched marine iguanas in the Galapagos Islands set off to join adults at the edge of the sea – only for a gang of racer snakes to emerge from caves and crevices.

"These snakes are fast, and hungry, and they want baby iguana for breakfast," says Sam Wollaston at The Guardian.

One iguana managed to outrun the snakes, but another newborn was not so lucky.

"What kind of a life is that, and what's the point?" asks Wollaston. "Birth, a few seconds of blind terror being chased by snakes (how do they know to run?), caught, crushed, pushed headfirst into a scaly mouth. And that's it, game – life – over. It's terrifying, I'm going to have nightmares."

Ellie Harrison at the Radio Times describes it as the "most intense chase scene of all time".

She writes: "Hell, those snakes could climb. And the sheer number of them. There were so many. It was a relentless, apocalyptic nightmare."

It wasn't just critics who were terrified. Viewers took to Twitter in their droves to react to the chase.

According to Christopher Stevens at the Daily Mail, the crew were "too shocked to film" when they saw the snakes for the first time. 

"Sir David had never seen anything like it either," he adds. "And that's the highest possible praise."