What lives in the flower pot's drainage pan

The drainage pans of the flower pots can easily accumulate water after daily watering or heavy rain.  The nutrients rinsed down from the drainage hole of the flower pot provides good source of energy for microorganisms. It's semi-enclosed space offers year-round environment suitable for microorganism to nurture.  What do I found it the drainage pans of my flower pots?

Two rotifers were trying to gather foods using cilias on the top of the coronas.

The drainage pans of the flower pots are perfect breeding place for mosquitos.