Understanding the Difference Between Cilia and Flagella

Difference between cilia and flagella
Cilia and flagella are protrusions on the surface of cells that carry out the function of propelling individual cells. This Buzzle post gives a cilia vs. flagella comparison in detail.
Did You Know?
The human hair is approximately 4000 times thicker than bacterial flagella.
We all know that all livings organisms have the ability to move from one place to another. But, have you ever thought how microorganisms move, for instance from one water film to another. Well, they too have structures or extensions that are attached to their cell body, which are used for locomotion.
Cilia and flagella are parts of a cell that help it to move. They are thin extensions that emerge straight out from the cell and provide motility to cells. Also referred to as organelles, they are primarily composed of proteins and play a crucial role in cell mobility. These locomotive structures consists of microtubules that act like propellers, thereby allowing them to swim in liquid media.
Also, cilia and flagella display very similar structures. These structures that are made up of microtubules are arranged in a 9 + 2 format. At the core lie two pairs of microtubules that are encased within 9 pairs of microtubules. However, these tiny propellers are different in the context of size, length, appearance, and the type of cell to which it is attached.
Cilia Vs. Flagella
Cilia micro organism
Flagella micro organism
Appearance
Cilia are tiny hair-like structures protruding from the cell body.

Flagella refer to whip-like extensions that grow outwards from the cell body.
Length
Cilia are significantly shorter than flagella and are usually 5-6 um long, but can grow up to 30 um in length.

Flagella length may vary, but can extend up to 10 times the cell length. Their length can go up to 1000 um. In simple words, they are long, freely rotating structures.
Thickness
Cilia , though short, tend to have greater diameter than flagella. They are around 0.3 to 0.5 um thick.

Flagella attached to the margin of the bacteria are around 20-25 nm (0.02 to 0.025 um) thin.
Density
Cilia are present in large numbers on the surface of the cell.

♦ Compared to cilia, Flagella are less in number.
Cell Type
Cilia protruding growths are visible in eukaryotic cells that include fungi (yeast), macrophages (white blood cells), protozoa, and sperm cells. The epithelial cells located in the respiratory tract also have cilia, which are used to clear the dust and germs away from the respiratory tract.

Flagella are dominantly present in prokaryotic cells. Bacteria, the single-celled organisms, that belong to prokaryotic cell type, often show a bundle of flagella attached to one point on their surface.
Motion
Cilia that are numerous on the cellular surface produce forward and backward vibrations. Their movements are similar to a paddle stroke. Their movement is often compared to oars of a boat that drive it forward in unison.

♦ The free ends of Flagella produce a whipping action, which means they have a rotary behavior. So, the prokaryotic cells rotate the flagella in both clockwise and counter clockwise direction, thereby enabling them to move in random directions.