Water Beetle

This guy looks like a water beetle larva to me. Well it looks like the one in the beautiful book 'African Insect Life"I've handled him so much I hope he survives till he pupates. It is about 5mm long at present and I have watched it since I first spotted it when it was about 2mm long. It has pretty lethal mouth parts and I have watched it attack and devour tiny as yet unitentified spherical animals that flit around in the water.