Thanks FlyFly - you've put my mind at rest. My DS is very scared of spiders, but I think he may be OK with this. If he knows it's just that, he can close his eyes and tuck his legs up - and if it's at the beginning, he can then relax for the rest.
It's amazing how scared you can be of nothing.
I sat in a listening booth at Conservation Station at AK, with headphones on in semi darkness. I could see people outside the booth and my DS and DH inside, but the sound of a cheetah (or something) growling right behind my neck really scared me. And I'm pretty fearless when it comes to animals (except swarms of the flying stinging sort!).