Jake Gyllenhaal found it "difficult" to deal with the snakes in 'Prisoners'.
The 32-year-old actor - who plays Detective Loki in the thriller drama - wasn't keen on working with the real-life reptiles on set and despite initially thinking he would be working with CGI - Computer Generated Imaginary - he admits being around up to 10 of the slithery creatures made the movie more believable.
Speaking on UK daytime show 'Lorraine' this morning, he said: "We had to deal with real snakes and real people - it was a difficult job. I think the reality of the movie was really important. I think a movie like this can go very easily into the genre elements or it can go quickly into the unbelievable."
The star - who is known for taking on complex roles - previously admitted he prefers to take on a role that has a hidden depth because he likes something that he can get his teeth into.
He said: "I look for something in the story that offers love in a more complicated way. I don't look for darkness, whatever that means, but in my mind, darkness acknowledges great light too.
"I think when it comes to a character, I'm moved by folk that I might struggle to love at first; characters that I have to do enough research on and think enough about to be able to really fall in love with them. Recently, in particular, that's what's been happening. I love Detective Loki. I found it hard to let him go."