About wheel animals
Wheel animals or rotatorier, contains the very common and abundant freshwater animals. The name is derived from the presence of a ciliate crown which, when beating, gives the appearance of a rotating wheel.
Wheel animals are among the smallest plural- celled animals known, under 0,5 mm, and approximately the same size of one-celled ciliates.
They are solitary free moving animals, but there are some sessile species as well as some colonial forms. The ciliate crown is situated at the anterior end for the body, which by their movements cause a current of water bringing nutrition to flow towards the mouth. At the same time the cilia propel the animal through the water. The opposite end of the body is prolongated into a stalk, or what is more often called the "foot". During locomotion the foot may be used as well as the cilia.
Reproduction is sexual. The males are always smaller than the females. Often the mails are present in the population only at certain times. The females are making eggs.
Parthenogenesis (without fertilisation) is characteristic for the group. The females can produce small males, which they later copulate with and make thick-walled resting eggs, often called winter egg. These resting-eggs will develop to females and start a new generation.
- Wheel animals