Rotifer. Light microscopy footage of a rotifer in meltwater from an ice sheet. Rotifers are microscopic organisms found in waters worldwide. They are mostly found in freshwater habitats, but some are found in marine environments. Rotifers are divided into three parts: the head, a trunk and a foot. The motion of cilia around the mouth sets up a current in the water, which draws in food, such as the decaying remains of plants and animals.