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Locomotory Organelles in Protozoa, Locomotion is the movement of an organism from one place to another in search of food or, shelter or partner or to escape from its predator., Protozoan shows different verities of locomotory organs, such as pseudopodia, pellicular, contractile structure, flagella, cilia., 1. Pseudopodia: Pseudopodia are false feet of some Sarcodina protozoans such as Amoeba., Pseudopodia are a temporary structure form by streaming of cytoplasm. It is comprised of, ectoplasm and endoplasm both. Pseudopodia are four types based on form and structure., a- Lobopodia: It is lobe-like pseudopodia with a round end, as in Amoeba. It moves by, pressure flow mechanisms. Lobopodia is found in Amoebic protozoan., b- Filopodia: Pseudopodia with the filamentous structure are called filopodia, these are, usually tapering at the base and pointed at the tip. Filopodia are composed of only ectoplasm, only. Example- Euglypha., c- Reticulopodia: It is also filamentous, which form branches, and branches of filaments are, inter-connected profusely to form a network-like structure hence, also known as rhizopodia., Example- Globigerina., d- Axopodia: These are some-how straight, and each axopodium has a central axial rod, covered by adhesive and granular adhesive cytoplasm. Example- Actinosphaerium., 2. Flagella, Flagella are the locomotory organ of flagellate protozoans, such as Trypanosoma, Euglena., Flagella are thread-like out projection on the body covering. Flagella of eukaryotic cells are, microtubular in structure. Microtubules are arranged in 9+2 arrangement in flagella but 9+0, arrangement at basal body or origin point of flagella. Energy for the beating of flagella is, mitochondrial ATP., 3. Cilia, Cilia are found in ciliate protozoan such as Paramecium. Cilia are resembling with flagella in, the basic structure such as microtubular in structure, microtubules are 9+2 arrangement cilia, and 9+0 arrangement at the basal body or origin point, but cilia are small in structure., Movement takes place by beating of cilia and energy for beating derive from mitochondrial, ATP, 4. Pellicular contractile structure, Some protozoans have the contractile structure in pellicle or ectoplasm or myonemes, such, as contractile myofibril in large ciliates, ridge, and groove in Euglena.

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Method of locomotion, The above describe organ beat in a different way causing different types of movement in, protozoans, so protozoans have several types of movement such as amoeboid, flagellar,, ciliary, and metabolic movement. Some of the protozoan movements are described here –, , 1- Amoeboid movement, Sarcodina, certain Mastigophora, and Sporozoa have characteristic amoeboid movement. The, process of amoeboid movement is done by pseudopodia formations, pseudopodia are, formed by streaming flow of cytoplasm in the direction of movement., , 2- Flagellar movement, Flagellar movement is present in Mastigophora, which bears one or more flagellum. There, are three types of flagellar movement that are recognized., a- Paddle stroke, This type of flagellar movement is first described by Ulehla and Krijsman in 1925. They, describe that in this flagellar movement of the flagellum is sideway consist of effective stroke, or down-stroke in the opposite direction of movement and relaxed recovery stroke, during, recovery stroke flagellum brought forward again and ready for next effective stroke. As, flagella give effective stroke in water in backward direction then water propels organism in, the forward direction., b- Undulating motion, In this type of movement wave-like undulation takes place from base to tip or from tip to, base. If wave-like undulation takes place from tip to base, the animal is pulled in the forward, direction, and if wave-like undulation takes place from base to tip animal is pulled in the, backward direction. And when undulation is spiral animals rotate., c- Simple conical gyration, It is described in Butschli’s screw theory, this theory postulates spiral turning like a screw. This, screw-like motion causes the pulling of the animal in the forward direction with spiral rotation, as well as gyration of the animal. Although the exact mechanism for this type of flagellar beat, is unknown, it is believed that axonemal fibers are involved in this process. Sliding tubules, theory describe, doublet slide past each other, which is the cause of movement in flagella,, and energy for this process is mitochondrial ATP.

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3- Ciliary movement, In the case of ciliary movement, the cilia oscillate in a pendulum-like manner. In each, oscillation, there is a fast effective stroke followed by the recovery stroke, like flagellar, movement. During effective stroke cilia expel the water in the backward direction like an oar, of the boat, and in response if this effective stroke water propels the animal in the forward, direction. During recovery stroke, cilia come in forward direction ready for next effective, stroke. Cilia neither beat simultaneously nor independently, cilia beat progressively in a, characterized wave-like manner., Mode of swimming by cilia, By ciliary movement animal directly does not follow the straight movement, they rotate, spirally like a bullet of rifle in left-handed helix manner. It might be because cilia do not beat, directly straight, beating is somehow obliquely toward the right and might be cilia at oral, groove beat more obliquely and vigorously away from the mouth. This combined effect, causes swimming movement in the animal., , 4- Metabolic movement, This is due to the pellicular contractile structure. In this type of movement, organisms show, gliding or wriggling, or peristalsis. Microtubules present in their pellicle is responsible for this, type of movement.