Rotifers are very little members of the animal kingdom, the largest being only just visible to the eye. They form an perfect early food for the fry of the larger species of fish. If these are put into an infusoria culture, they’ll thrive.
Rotifers are discovered in ponds generally among the weeds, and one species, Brachionus rubens, might be discovered clinging to the body of daphnia. These are removed by washing the daphnia in a fine strainer under a jet of water.
The rotifers then turn out to be detached and fall via, and also the daphnia remain. When collecting rotifers a very fine net should be utilized; fine muslin will do.
Rotifers are divided into four classes; those that live in tubes, those that swim freely, those that creep like a leech, and those that progress by leaps-making altogether 700 species.
They’re also referred to as ‘wheel animalcules’ simply because of the rapid movements of the cilia which surround the fore component of the body, giving the illusion of a rotating wheel. They reproduce themselves by eggs.