What kind of bug is this?

Last night I was out on Nolin River Lake in Kentucky (37.318, -86.248) and this bug came up in to the light from the lantern I had hanging over the side of my boat. I've been fishing in this lake for most of my 41 years and have never seen anything like it. It's probably between one to two inches long and it didn't swim by moving its legs that I could see and I can only guess that it moved in the water by expelling water, sort of like a jet drive. I could be wrong about its method of propulsion but I did watch it circle around in the light for roughly 10 minutes before I caught it with a minnow dip net so I could get a decent picture, after which I released it unharmed and it swam off. I looked on multiple web sites and there were a few bugs that are similar but each of them have distinctive features (long, thin antennae mainly) that this thing just did not have. So I am wondering if anyone here might have some clue as to what it is?



Here are the sites I checked:

University of Kentucky Entomology

http://ift.tt/1FJ0Yq1 - Links to a PDF

http://ift.tt/1cUUucm

via International Skeptics Forum http://ift.tt/1cUUwB3