stinging nettles

My hermanns tortoise Dash really likes nettles but i think they are stinging him!! Today he had the strangest reaction to eating them. He jerked around, opened his beak really wide and moved his head from side to side as if they were stinging him. He just kept eating them but eventually i took...

I saw some websites saying you can feed stinging nettles to tortoises, is this the ones that you get stung and they really hurt here in the uk or am I being dumb? If so does it sting tortoises and can I feed it to my russian or is it just certain species of tortoises?