Physical Description
The paramecium is shaped sort of like a football, rounded at the
front/top and pointed at the back/bottom. The pellicle, a stiff but elastic
membrane, is what gives the paramecium its definite shape but allows some
small changes. Covering the pellicle are many tiny hairs, called cilia.
On the side beginning near the front end and continuing down half way is
the oral groove. There is an opening near the back end called the anal
pore. The contractile vacuole and the radiating canals are also found on
the outside of a paramecium.
Inside the paramecium is cytoplasm, trichocysts, the gullet, food vacuoles,
the macronucleus, and the micronucleus.
Roles of Features
Pellicle- protects the paramecium and keeps things out
Cilia- help paramecium move and sweep food into the oral groove
Oral Groove- collects food until it is sweeped into the cell mouth
Cell Mouth- where food enters
Anal Pore- disposes of waste
Contractile Vacuole- contracts and forces extra water out of the cell
Radiating Canals- paths to the contractile vacuole
Cytoplasm- intercellular fluid which helps the paramecium carry out functions
Trichocyst- used for defense
Gullet- forms food vacuoles
Food Vacuole- storage pocket for food
Macronucleus- larger nucleus which performs normal cell functions
Micronucleus- smaller nucleus which is responsible for cell division.
Senses
The five senses are sight, touch, scent, taste, and hearing. The paramecium
does not have any of these senses.
Locomotion
The paramecium moves by swimming. For the paramecium to move forward the
cilia beat on an angle, backward. This means that the paramecium moves
by spiralling through the water on an invisible axis. For the paramecium
to move backward, the cilia simply beat forward on an angle.
If the paramecium should run into a solid object the cilia change direction
and beat forward, causing the paramecium to go backward. The paramecium
turns slightly and goes forward again. If it runs into the solid object
again it will repeat this process until it can get past the object.
Gathering Food
Paramecium feed on microorganisms like bacteria, algae, and yeasts. In
order to gather its food the paramecium uses its cilia to sweep the food
along with some water into the cell mouth after it falls into the oral
groove. The food goes through the cell mouth into the gullet, which is
like the stomach. When there is enough food in it so that it has reached
a certain size it breaks away and forms a food vacuole. The food vacuole
travels through the cell, through the back end first. As it moves along
enzymes from the cytoplasm enter the vacuole and digest it. The digested
food then goes into the cytoplasm and the vacuole gets smaller and smaller.
When the vacuole reaches the anal pore the remaining undigested waste is
removed.