The grass snake (Natrix natrix) may not be venomous like the adder (Vipera berus), but they do posses some other unique ways of fending off a possible threat.
1. If you startle a grass snake and it feels like it has no means of a quick escape, it will sometimes rear up like a cobra. The female grass snake in the photograph below did just that and at around 120cm in length, with approx 1/3 of her body raised in the air, she was quite intimidating.
2. If a grass snake is attacked, or if it feels like its life is in danger, it will sometimes feign death. Basically it will squirm around and come to rest upside down with its mouth gaping and tongue hanging out.
I do not have any photographs of this as I have never put a grass snake in this situation, where it feels threatened to this degree. I cringe when I see photographs on the internet of grass snakes doing this, as I know that they have been, or are enduring immense stress!
3. To accompany the death throws and if disturbed, the grass snake will sometimes squirt a "foul" smelling liquid from its anal gland. If this doesn't sound bad enough, just imagine what rotten fish and anal secretions must smell like and you are almost there. If you get this on your clothes or skin, it is very hard to wash away and the smell makes you feel sick!
A grass snake of 120cm pretending to be a cobra. I was lying on the ground for this shot and her head was higher than mine. Awesome encounter with a truly beautiful snake.
I still see her today on occasions, 4 years later and she looks a lot bigger.