The corona is modified extensively in some species. The mastax is a muscular pharynx containing a complex set of hard jaws or trophi and is found in all rotifers. These characteristics of these structures have been used extensively in classifying rotifers. Rotifers are small animals, ranging in size from 100 to 2500 microns. Most species are free-living herbivores, bacteriovores or predators.
Rotifers move by swimming or crawling.
Some sessile species are permanently attached to freshwater plants. Rotifers display a variety of reproductive modes. Individuals in the class Monogononta generally reproduce by cyclical parthenogenesis. Females reproduce asexually for the most part, then in response to environmental cues they produce daughters that are capable of producing eggs by meiosis. These haploid eggs develop into males if they are not fertilized.