Rotifers Life Cycle

Rotifers are small aquatic animals that can be found in fresh water and moist soil. They can live in both still water and flowing water locations, including lake bottoms and rivers. Rotifers play an important role in the aquatic food chain because they eat microorganisms, and are subsequently eaten by others. They are micro in size, ranging from 200 to 500 micrometers in length.

  1. Appearance

    • Rotifers are considered to be animals because they have a full digestive system, and despite the face that they are microscopic in size. Male rotifers do not typically grow in size, while the females reach full size quickly. Female rotifers are always larger than the males, sometimes reaching up to 10 times the size of their male counterpart.

    Classes

    • There are three different classes of rotifers: monogonta, bdelloidea and seisonidea. Acanthocephala is at times considered a class of rotifer as well. Each class has a number of different species. The monogonta class is the largest class of rotifer, with 1,500 different species. The seisonidea class is the smallest class of the three, consisting of only two different species that are known.

    Breeding

    • Reproduction and breeding of rotifers varies from class to class, and is sometimes dependent on species. The bdelloidea class of rotifer, for example reproduces only asexually, while the monogonta class of rotifers can alternate between sexual reproduction and asexual reproduction. A female rotifer has one or sometimes two ovaries. Fertilization happens internally. The eggs that are created are usually attached to plants or the outside of the female's body, but some species keep the eggs inside of them until they hatch.

    Eggs

    • When a male is present for reproduction, he inseminates the female, which fertilizes resting eggs. When a male is not present, reproduction happens by parthenogenesis. When the eggs hatch they look like smaller versions of an adult.

    Life Span

    • A female rotifer from the monogonta class has a life span of only a couple of days to three weeks. Males have a shorter life span than females, and so are usually fertile when they hatch. Their life span is shorter than a female's because their digestive system is usually not functional.