A couple of weeks ago I noticed that the strange looking larva of the lesser diving beetle Acilius sp. (probably sulcatus) swimming around in a pond. I quick went and got a net and caught one, before taking it inside to photography in my aquarium set up.
There was a very brief struggle before the paralysing and digesting fluid injected by those fangs got to work. It then, unlike the larva of its larger relative the great diving beetles (Dytiscus sp.) seemed to be munching through its prey.