One pond sample I have is full of caddisfly larvae. I had just made up a couple small "tanks" to photograph this type of critter, so I thought I would try them as my first subjects. When I went to collect a couple I saw one that had "exited" the protective tube that they make (and drag around with them). I had not seen this before, but I assume they occasionally need to make new tubes as they grow. I put it in the mini-tank. Then I found one that was dragging around a nice patchwork tube. I put it in as well. Now I knew some caddisfly larvae are predators, but I thought these were "vegetarians". Well, as soon as they bumped into each other the one with the tube went after "tubeless" larva like a pit bull that hadn't eaten for a week! In the lower photo you can see it chowing down on it's hapless victim. Ate it from head to "toe".
The white threadlike structures on the one being eaten are gills that are normally covered by the tube.
BTW... a while ago I wanted to see how they managed to cling so doggedly to their tubes as they crawled around. So I put one under the microscope. They have rear prolegs with some pretty impressive hooks with which they grab onto the tube. Have a look here:
http://www.photomacrography.net/forum/v ... php?t=2115
Anyway, a great follow up to that previous post. I had read off and on, here and there, that these things were predacious but had never seen them in action. Really some amazing images. 
