I've decided to use a different structure to my animation. I've realised that the first two scenes can build very slowly, with the music slightly getting louder, the two scenes are below, the Forest Opening shot and the panning through the 'leaf' canyon towards the Sporangium:
The Sporgangium will look different as Klappa described their proper appearance (Shorter stalk) but the cave scene will be very slow, building up as the camera moves closer. Once the camera gets close the pods quickly spring open and all the spores fly out, this is when the music's pace increases. The structure from there on is very similar to the animatic, only faster-paced, the main scene I'm focusing on is the 'rapids' - the sperm flowing down the leaf towards the egg.
I'll post a revised animatic sometime this week, but firstly, I want to get cracking with some Maya.