Gary Montz (audio #1)
"Another little creature that lives in rivers is a baetisca or an armored mayfly. This is a tiny little mayfly and you'll find it in the shoreline areas of rivers in sand and silt bottoms. It's got a neat little adaptation to help it live in this habitat. You'll see on the back of it there's a hard, shell- like carapace and it's got a lot of points sticking out. This helps hold its position in the sand or silt with the current coming across it. The carapace also serves another purpose, a real important purpose: you can see that it covers the delicate gills for the mayfly and it can lift the carapace and let the water come in and not allow the sand and silt to clog the gills so the mayfly is able to breathe."