Cilia and Flagella are cell organelles which protrude out of cytoplasm and are meant for external functions of cells. Cilia are small hair like structures coming out of cytoplasm of many animals and cells.
Flagella are long thread like or whip like structures protruding out of cytoplasm through cell wall.
Cilia and Flagella are cell organelles that look similar, but they have a wide range of differences
| Sl. No | Characteristics | Cilia | Flagella |
| 1 | External Morphology | Short, slender, hair-like structure | Long, filamentous, thread- like structure. |
| 2 | Occurrence | Seen only in Eukaryotes. | Seen in both Eukaryotes and Prokaryotes. |
| 3 | Distribution | Class Ciliata and members of other classes, ciliated epithelium of Metazoa, larvae of Annelids, Molluscs, Echinodermates, and Platyhelminthes | Class Flagellata, Choanocyte of sponges, spermatozoa of the Metazoa, Algae, and gamete cells. |
| 4 | Position on the cell | Seen throughout the surface of the cell. | Seen in one or two ends or all along the surface of the cell/ organism. |
| 5 | Density | Numerous | Only a few |
| 6 | Length | Ranges from 1 -10µm | 5 – 20 µm, sometimes measure up to 150 µm. |
| 7 | Width | Less than 1 µm. | Ranges from 10 – 30 nm. |
| 8 | Function | Locomotion, feeding, circulation, aeration, signal transformation in sensory cells, expelling particulate matters in the respiratory tract, etc. | Locomotion only. |
| 9 | Types | 1. Primary cilia or non- motile cilia (seen in almost all the cells). 2. Motile cilia (seen in respiratory passages like nose,pharynx, and trachea; middle ear, etc.) | Bacterial flagella Archaeal flagella Eukaryotic flagella. |
| 10 | Types of motion | 1. Fast-moving, rotational, show back and forth beating. 2. Show rhythmic, coordinated movement. 3. Ciliary movement sweeps materials across tissues. | 1 Slow-moving, propeller-like motion, undulating, sinusoidal movement. 2 Show independent movement. 3 Flagellar movement propels cells forward |
| 11 | Energy resource | Use ‘kinesin’ which has ATPase activity | Obtain energy from Proton the motive force of the plasma membrane. |
| 12 | Internal structure | Motile cilia: 1. It contains an outer membrane that encloses cilia, which fuses with the cell wall at the base. 2. Bounded space contains a fluid matrix. It has microtubules. 3. It has 9 fused microtubule doublets that surround 2 central single microtubules (9+2). 4. This arrangement is collectively called an axoneme. 5. Microtubule doublet contains ‘A’ tubule and ‘B’ tubule. ‘A’ tubule is a complete tubule with 13 protofilaments. ‘B’ tubule is incomplete with 10 protofilaments. Primary cilia 1. The matrix contains 9 fused microtubules only (9+0). There is no central tubule. | Eukaryotic flagella 1. Shows similar internal morphology of motile cilia of eukaryotes. 2. It contains ‘axoneme,’ which has a 9+2 microtubule arrangement. 3. Thicker. Prokaryotic flagella 4. There is no 9+2 arrangement of microtubules. 5. Prokaryotic flagella are made of a protein called Flagellin. 6. Thinner when compared to eukaryotic flagella. |
| 13 | Presence of Nexin | Nexin protein is absent | Nexin protein is present between the tubules to hold them together. |
