In their natural environment rotifers thrive on a multitude of algae and microbial detritus that they find in suspension in the water column. As obligate
filter feeders they ingest particles up to 20 μ without discrimination for shape or nutritional composition (Baer et al., 2008).The irregular shape of the non-digested food fraction is compressed in the last part of the digestive system and compressed as a fecal pellet.
The expelled fecal pellet being bigger (app. 30μ) than what a rotifer can ingest it sinks relatively fast to the bottom where it is further decomposed.This natural mechanism is a unique way to avoid pollution in the water column (Feinberg and Dam, 1998) and prevents direct
contamination of fecal material among the population.