The paramecium has a stiff outer covering that gives it a permanent slipper shape. Its length is varies from 80 to 350 miu. It swims rapidly by coordinated wavelike beats of its many cilia-short, hair like projections of the cell.
A paramecium normally moves forward in a corkscrew fashion but is capable of reversing direction when it encounters adverse conditions. Direction until an optimum path is found is conspicuous when the animal is observed through a microscope.
Paramecia and other ciliates are the most complex of all single-celled organisms. There are also an anal pore, two contractile vacuoles that regulate the water content of the cell, and two nuclei. The larger nucleus, or macronucleus, is thought to regulate most cell functions, while the smaller nucleus, or micronucleus, is involved in reproduction, white orgery dot with naked eye.