Question

What is the morphology of Protozoans? What are the microscopic methods to observe the morphology of Protozoans? Discuss the methodology of Euglena microscopy.

Answer 1

Protozoans:

• Currently approximately 39,000 known species of protozoans are present.
• General characteristics of this include body form , organization, size, symmetry, body structure, organelles of locomotion, nutrition, respiration, excretion, osmoregulation, reproduction, encystment and habitat.
• Classification: The classification of protozoa was given in 1964 by B.M.Heinberg.

                               

                            

 

• The morphology of the protozoans can be observed microscopically by either transmission electron microscopy or scanning electron microscopy.

 Morphology of Protozoans:

• Protozoa are eukaryotic resembling to animal cell, contain major cell organelles which includes nucleus, mitochondria.
• Their organelles are highly specialized for feeding, reproduction and movement.
• The cytoplasm of protozoa are divided into an outer layer called ectoplasm (helps in movement, feeding and protection) and an inner layer called endoplasm (houses nucleus, mitochondria and food).
• Some protozoa have special appendages flagella and cilia which helps in their movements.
• Freshwater protozoa have contractile vacuoles to pump out excess water.
• Their shape may remain constant or change constantly.
• Its size ranges between 3-300mm.
• Few ciliate and amoeba are larger enough to be seen with naked eyes (they are about 4-5mm).
• Except sporozoates, all the types of protozoa are motile either through flagella, cilia or pseudopodia.
• Has eyespot which detects the change in light.

Microscopic Morphology of Protozoans:

• The morphology of the protozoans can be observed microscopically by either transmission electron microscopy or scanning electron microscopy.
• The protozoa is usually stained and observed while illuminated and is  useful for observation of the gross morphological features.
• The procedure for microscopy of protozoa includes following steps:

1. By using a dropper, place few drops of the sample on a microscope glass slide . 
2. Gently cover the sample with a cover slip.
3.  And then mount on the microscope stage for viewing.s
4. Finally, start with low power and increase gradually to observe the specimen.

Now let us discuss the Euglena microscopy -

Euglena Microscopy:

• Euglena are single celled organisms so they cannot be seen with the naked eye.
•  As result of this reason, a compound microscope has to be used to observe and study them. 
• They are found in algae or pond weed in pond water.
• Euglena  has an eyespot at their anterior end which serves to detect light.

Procedure of euglena microscopy includes the following steps:

 

1. By using a dropper, obtain some pond water or the brown scum from the culture.
2. Now place a drop of the sample on a microscope glass slide.
3. Then place the cover slip gently on the sample and finally place the slide on the microscope stage for observation.

Observation of Euglena:

• Under microscope at 40X, Euglena appear like tiny particles making small movements in the water.
• By increasing the magnification to 100x and 400x, we will notice that they appear green/light green in color with dark spots inside as well as a whip like tail.
• Still more magnification, will also show colored granules, which are referred to as the eyespot.
• A blunt (rounded) end portion and a pointed end is observed.
• Under more powerful electron microscopes, it have revealed the presence of an ornamented pellicle under the plasma membrane.

 

Protozoans:

• Protozoans are microscopic, acellular and eukaryotic animalcules found either solitarily or in colonies generally in aquatic medium or as parasite.
• It was first discovered by A.V.Leewenhock in 1672.