Many organisms walk a fine line, balancing their need for food with their need to avoid predation. Minnows in Texas are no exception to this rule. On a cold day (around 50 degrees Fahrenheit) with no precipitation and partial clouds, I observed several minnows on the edge of a local pond (I observed within a foot of the edge of the pond).  The minnows ranged from about two to about four inches long and appeared to be of the same species and of the family Ciprinidae (Nelson, 2000). The pond had algae and debris lining its edge.

While I was watching the minnows, I noticed that they would continually flick around in a very excited manner. Flicking involved very short, fast movements, in which the minnows usually moved less than an inch in a second or less. Usually, this flicking would bring them to the top of the pond, or even closer to the shore. When the minnows moved, they also appeared to be nibbling on the algae in small bites – taking one nibble and then “flicking away”. Additionally, the minnows moved independently, but seemed to stay around the same group of other minnows. Finally, if I moved and a shadow passed over the water, the minnows would dart away. Their darting had them moving quickly, like with flicking, but in longer strokes – when darting the minnows usually moved out of eyesight, but definitely more than a few inches.

While watching the minnows, I developed several hypotheses regarding what evolutionary advantages some of their behaviors may have served. (more…)