Answer:
Ciliates
Explanation:
The ciliates refer to a group of protozoans featured by the existence of hair-like organelles known as cilia that are similar in composition to eukaryotic flagella, but are in usual shorter and existing in much larger quantities, with a distinct rolling pattern than flagella.
These species are not considered as producers in the food chain and as producers of oxygen due to the absence of chloroplasts.
