Paramecium are a genus of organisms within the kingdom Protista, which represents single cell organisms and some multicellular algae. While the organisms in the more familiar plant and animal kingdoms are composed of many cells that work together to fulfill the animal or plant’s biological functions, single celled organisms like the paramecium must do everything required for life—take in nutrition, eliminate waste, produce energy, and reproduce—within the confines of a single cell. As such, the single cell of a paramecium has many functions.
While not all single celled organisms need necessarily move around—some, like many bacteria, are stationary—the paramecium uses movement to find food. In order to accomplish this, the outside of the cell is equipped with cilia, which resemble small hairs. As the cilia beat rhythmically, they propel the cell through liquid. The University of Massachusetts notes that paramecia are very flexible, and because of their cilia and oblong shape, they are quite maneuverable.
Ingestion of Nutrients
As a result of their mobility, paramecia can search out food. They consume small algae and plants, which they ingest through sweeping the food into mouth-like structures called buccal cavities. Just as cilia surround the outside of a paramecium, they also line the buccal cavity, where they act as little brooms, helping to draw in liquid that contains food particles. The University of Massachusetts explains that food then passes through a structure called the cytopharynx, which is similar to the human throat. While paramecia have no stomachs, they do tuck food into small structures called vacuoles, which contain digestive enzymes. Here, digestion takes place.
Living organisms, by definition, must reproduce. While many organisms accomplish this through the combination of the genetic material of two different organisms, producing an offspring that represents a mixture of the parents, paramecia do not have to engage in sexual reproduction. Instead, a single paramecium can into two, copying its genetic information and providing one set of the genes to each of the two daughter cells. All structures within the paramecium copy themselves, such that when the organism splits, each daughter is a perfect reproduction of the parent, albeit in miniature. In their textbook “Biology,” Drs Neil Campbell and Jane Reese explain that paramecia can also reproduce sexually, through a process called conjugation, in which genetic information is transferred between two organisms, resulting in recombined genes, which are then copied and passed to daughter cells.