Where exactly did you find it, and about how big is it? It looks to me like some kind of parasite, maybe a larval stage of a fluke? Can you describe the way it was swimming - for example wriggling like a tadpole, or more jerky like a gnat larva maybe?
The first picture was taken at 40X magnification (I think it's about a mm in length) and the second one at 100X. It moved using it's middle body swimming in the medium very slowing and ate using it's front "teeth?. It was swimming with the bulb part behind using the long part of the body to propel forward (kind of like a snake but very slowly). A fluke sounds about right since it was found in a stool sample but I haven't seen one quite like this with the stripes along the bulb. Here are some more pictures close up. Thanks for responding. I am curious as to what kind of parasite it is exactly.
Sorry, can't help with exact ID but hopefully there are some experts here who can. It looks like a cercaria larva of a fluke to me, but I've never seen a live one moving, so can't be sure about that. If it was from a particular animal you can look up parasites of that animal (or bird or fish or reptile?) In any case, hope you handled it with gloves!
You said "It ate using its front "teeth". How exactly? Were the "teeth" on the bulb part? Are you sure it was eating? It may just have been holding on. Parasites often have suckers and/or spines to hold on with or to anchor part of the body when moving.
Perhaps you should repost your question in the ID forum, you would be more likely to get an answer there.
The nearest I can find are here: http://www.visualphotos.com/image/1x7606131/fasciola_hepatica_cercaria_common_liver_fluke They have "stripes" like the one you found.
If they are liver flukes (eg from sheep droppings) you may need to get a medical check up in case - they can infect humans too.
Thank you so much Drosophila for your help. It is a mystery. The "teeth" or whatever they are... are on the long end (second picture) away from the bulb. It may have been trying to hold on as well. It was swiming with the bulb end behind so I'm assuming that the front end is the long end and the bulb is the rear. Yes, I definitely wore gloves... I hope that someone who knows does respond. I am very curious. If not, I'll take your advice and post it on the other forum. I wish I could download the video.