An interesting posting Adrian. I've tried photographing tadpoles "in the wild" with very little success but you've managed to capture quite a lot of detail in this pic.
This little fellow looks to be well on the way to taking his first hop.
The water in which i photographed them was quite shallow in some parts, they where pretty scrambly too, but as i took the time to look, some of them where very still, like this one, maybe trying to camouflage it-self.
I found that generally the photographs from side on - to the waters surface, come out bad due to the waters distortion, but photographs parallel to the surface come out best, like this one.