Rotifer

Rotifers are tiny animals that grow less than 1 mm in length. Majority of them live in fresh waters. They can be sedentary or swimming freely. Their body is covered with epidermis that can have rigid layer (lorica) mainly on thorax. Rotifers have a rotary organ on their head (corona) that gave this group its name.

Corona consists of two ciliar spots that are shaped like rings (trochus). By beating their cilia rotifers gain their food or move. Circulatory and respiratory systems are not developed. Rotifers have separated sexes. Females can reproduce without a male (parthenogenetically). Males are much smaller than females, don´t have digestive system and live only shortly. Anabiosis is quite common in soil living species. During anabiosis animals are dry, covered by a mucous capsule that can protect them for several years without water until suitable conditions reappears.