CiliaFine hairs set in close rows over the whole surface. They beat to drive the paramecium through the water, and those in the oral groove sweep food toward the gullet.
PellicleThe stiff but elastic covering of the whole cell. The cilia pass out through it, and the trichocysts sit just under it.
TrichocystsTiny spindle-shaped sacs set just under the pellicle. When the cell is disturbed they shoot out long threads, which is thought to be a defense.
Feeding 4
Oral grooveIts cilia beat all the time and draw food toward the gullet. A hollow that runs from the front of the cell back to about its middle.
Food vacuoleA bubble of food pinched off at the end of the gullet. It is carried round the cell while the food in it is digested.
GulletA funnel-shaped passage from the oral groove into the cell. Also called the cytopharynx. Food vacuoles form at its inner end.
Anal pore (cytoproct)The spot where undigested waste leaves the cell. It is on the oral side behind the groove. Older books call it the anal spot.
Nuclei and water 3
MacronucleusThe larger of the two nuclei. It runs the everyday work of the cell.
MicronucleusThe smaller nucleus, beside the macronucleus. It carries the genetic material that is passed to the next generation.
Contractile vacuoleOne lies near each end of the cell. Arms that radiate from it gather excess water, the vacuole swells, and then it squeezes the water out of the cell.
How this list was compiled: Every name was checked on 2026-09-30 in two places, for facts only and with nothing copied. (1) R. W. Hegner, An Introduction to Zoology (1910), the chapter on Paramecium, https://archive.org/details/introductiontozo00hegnrich, and the same author's College Zoology (1912), https://archive.org/details/collegezoology00hegn; both are in the public domain. (2) Wikipedia, text only: Paramecium, Cytostome, Macronucleus, Micronucleus and Trichocyst, for example https://en.wikipedia.org/wiki/Paramecium. (3) For the modern name cytoproct and for the arms of the contractile vacuole: journal abstracts on Paramecium read through Europe PMC, https://europepmc.org/article/MED/19120793 and https://europepmc.org/article/MED/12421576. Licence: own work
The drawing: Drawn for this site on 2026-09-30 from plain geometry; nothing traced. Licence: own work
How it works
This paramecium diagram labeled for biology class shows the cell from the side, front end on the left. Tap a name to read what the part does, then press Quiz me.
Read the full guide
Follow the food through this paramecium cell diagram
Cilia in the oral groove sweep food to the gullet. At the inner end of the gullet the food is closed into a food vacuole, which is carried round the cell while it is digested. What is left over leaves through the anal pore.
Two nuclei and two water pumps
The large macronucleus runs the everyday work of the cell. The small micronucleus beside it carries the genetic material passed on to the next generation. A star-shaped contractile vacuole near each end pumps out excess water.
On a paramecium labeled diagram the blunt end is the front: the cell swims with that end first.
Cytopharynx is accepted for gullet, and cytoproct or anal spot for anal pore.
Questions and answers
What are the parts of a paramecium?
Cilia, a pellicle with trichocysts under it, an oral groove, a gullet, food vacuoles, a macronucleus, a micronucleus, two contractile vacuoles and an anal pore.
Why does a paramecium have two nuclei?
They do different jobs. The macronucleus controls the daily work of the cell, and the micronucleus holds the genetic material that is handed on when paramecia reproduce.
What do the cilia do on a paramecium?
They beat in waves to move the cell through the water, and the cilia of the oral groove draw food in.
What does the contractile vacuole do in a paramecium?
It pumps out the water that keeps entering the cell by osmosis from the fresh water around it. There is one near each end of the cell.