Rotifera (Latin: rota, wheel; fera, to bear) is a phylum within Kingdom Animalia. The rotifers are microscopic aquatic psuedocoelomates.


The rotifers have a ciliated mouth called a corona, which they use to collect food and for locomotion. The beating of the cilia gives the illusion that this animal has a wheel attached to its jaw. The corona creates a water current into the mastax, which is composed of several sets of jaws called trophi. From there food passes to the stomach, is digested by enzymes, and exits the anus.

Rotifera Classes and Orders differ in the way in which they reproduce. In Bdelloidea males are completely absent and reproduce by parthenogenesis. Members of Seisonidea produce haploid eggs which must be fertilized. Monogononta produces two types of eggs:

  • Amictic: Diploid eggs formed by mitosis, which develop directly into females without fertilization.
  • Mictic: Haploid eggs which, if unfertilized, develop into males. If they are fetilized these eggs will encyst themselves and await hatching in the spring.


Classes within Rotifera

Class Digononta

Characterized by paired ovaries.

Order Seisonidea

Only two species, both of which are Epizoic (living on the outside of an organism) to crustaceans; reduced corona. Males and females are both needed to produce offspring.

Order Bdelloidea

More than five hundred species. Mastax is used for grinding, males absent.

Class Monogononta

More that a thousand species. Mastax not used for grinding; males are less numerous, females produce Mictic and Amictic eggs. Contains the orders Collothecacea, Flosculariacea, and Ploimida


Campbell & Reece. "Biology" Benjamin Cummings. 6th Edition, 654
Introduction to Rotifera
Miller & Harley. "Zoology" McGraw Hill. 7th Edition, 176-179
Rotifer Systematic Database