Most planarians are carnivorous and feed on protozoans, tiny snails and worms, says the Encyclopædia Britannica. They devour the living as well as the dead, decaying organic matter as well as diatoms.
These flatworms are known for their ability to regenerate themselves completely from the smallest body part possible and to withstand vast fluctuations in temperature. According to the Genome Institute, freshwater planarians can be found in a wide variety of often harsh running water aquatic settings, such as streams, springs, rivers or ponds. They are usually found at the bottom, sticking to hard surfaces, such as underneath rocks and gravel.