Squirmy minnows (mayflies)!

Imagine you are hiking by this small, lovely stream in upstate New York. Your big human foot crunches down on some shale next to one of the clear, gravelly pools and you can't help but notice one hundred dark little squiggles bolting and squirming in every direction in response to the tectonic disturbance that just rippled through their watery home. Your brain immediately thinks "fishies!" or, maybe, "tadpoles!" However, tadpoles prefer still water and fish are generally found in larger waterbodies. The little squirmers you saw are probably lacking a backbone and may, in fact, be mayflies! Take a close look at the video below. I snuck up on a few of these critters and gave them a gentle poke so you could see how fish-like their motions can be. I apologize for the video quality. I took the video with my camera and will, at some point, acquire some better gear.

See how many mayflies you can find in the picture above. Mayflies are one of many orders of insects that have an aquatic juvenile stage. In other words, after these insects hatch out of eggs, the spend a period of time in water eating and growing before they transform completely in appearance and emerge onto land to mate. The mayflies shown here are commonly called "comb-mouth minnow mayflies." The "minnow" part of the name refers to their fish-like appearance and movements. The "comb-mouth" refers to the shape of their mouth parts which they probably use to gather and scrape very small pieces of food (e.g., periphyton, diatoms) off of rocks. They are in the family Ameletidae and in the genus Ameletus (in case you like taxonomy). Ameletus is considered very sensitive to environmental pollution/disturbance. Thus, you are most likely to find them in small streams in wooded areas and are unlikely to find them in streams in agricultural fields or urban areas. Enjoy the close-up of Ameletus below ( Donald S. Chandler/ Discover Life ).If you want to see what this animal looks like when it emerges onto land click here. I highly recommend going out and seeing what kind of creatures you can spot in a stream near you. You can get your hands wet and gently turn over rocks or you can just spend a little time gazing into the watery realms watching the sunlight flicker over rocks and leaves while listening to a singsong babble. A very useful yoga pose for watery gazing is the stream side squat (shown below).