Paramecium is a group of unicellular ciliate protozoa. They belong to the kingdom protista, class ciliatea and family parameciidae. Paramecium size ranges from about 50 to 350 μm in length. The cell is covered by cilia (short, hairlike projections of the cell), which allow the cell to move with a synchronous motion. One of the interesting paramecium facts is that it has a deep oral groove from where food is drawn inside. Paramecia generally feed on bacteria, other small cells, yeast or small algae. The cilia help catch the food which is then forced down a little tube called a gullet, that leads to the protoplasm or stuffing of the cell. The food is held in little vacuoles. The stiff outer covering of the paramecium gives it a permanent 'slipper' like shape. The exterior membrane of the cell is known as 'pellicle'. It is stiff as well as flexible. Some flexing of the surface is possible because of this membrane. The cilia help paramecia to move. They can move at speeds of approximately 2,700 μm/second (12 body lengths per second). One of the amazing paramecium facts is that although it normally moves forward in a corkscrew manner, it is capable of reversing its direction when it encounters an adverse condition. Paramecium reproduction usually takes place asexually, by cell division; but the unicellular organism can even interchange the genetic information through a process called conjugation. Just like amoeba, the paramecium cell splits in half (fission). Initially, the smaller nucleus divides itself into two halves and each half goes to either end of the paramecium. Then the bigger nucleus divides and the whole paramecium splits. During the process of conjugation, two paramecia join at the oral grooves and interchange micro-nuclei that are in fact nothing but little packages of DNA. After the union, the cells divide, producing daughter cells with DNA from each of the parents.