Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.
Dragonfly nymphs propel themselves through the water with a miniature jet engine, taking water in below their mouths and shooting it out their back ends. You can see the ripples from the jet out this one's back in this video.
This little Ephemera nymph swam around for a while and tried to burrow into the sand in my photography tank.