Question

single celled organism lives in water​

Answer 1

Euglenophyta, flagellated, mostly unicellular algae that occur often in fresh water. In contrast to most other algae, they lack cell walls and can be mixotrophic (both autotrophic and heterotrophic). An example is Euglena gracilis. Chlorophyta (green algae), mostly unicellular algae found in fresh water.