Light micrograph of the rotifer worm Platyas quadricornis. This free-swimming, aquatic micro-organism has a body which is divided into three sections. The head (top centre) possesses many cilia (not clearly seen) which surround the mouth. These are used for catching food particles suspended in the water. The rounded body ends with a short foot (lower left), on which are two adhesive "toes" (bottom), used for anchoring the animal to a substrate. Dark field illumination. Magnification: x260 when printed at 10 centimetres across.