Algae vs Protozoa
All organisms are grouped into five kingdoms. Those are Monera, Protoctista, Fungi, Plantae and Animalia. The division is made based on 3 criteria. Those are cellular organization, arrangement of cells, and type of nutrition. Cellular organization is whether they are eukaryotic or prokaryotic. Cell arrangement is whether they are unicellular, multicellular, with or without true tissue differentiation etc. Type of nutrition is whether they are autotrophic or heterotrophic. Kingdom Protoctista includes algae, protozoans, oomycota and slime moulds.
There are four phyla in kingdom Protoctista, which includes different types of algae. Those are phylum Chlorophyta, which includes green algae, phylum Phaeophyta that includes brown algae, phylum Rhodophyta, which includes red algae, and phylum Bacillariophyta that includes diatoms. Algae are a large group of organisms (protoctistans) that are of high biological importance. They are often photosynthetic eukaryotes living in water. Algae can be found in both marine and fresh water. Body of algae lacks stems, leaves or roots. Therefore, their body is called a thallus. Algae are grouped into different phyla based on the type of their photosynthetic pigments. All those phyla have some general characteristics in common. Almost all are well adapted to the life in water. They show a large diversity among the group members in terms of size and form. They include unicellular, filamentous, colonial, and thalloid forms.
Protozoans are animal like. That is they lack a cell wall, and they have ingestive type nutrition. The organisms are always unicellular. One common example of a protozoan is Amoeba. Amoeba is aquatic, free living and omnivorous. The cytoplasm is differentiated into an outer ectoplasm and an inner endoplasm. This animal is uni nucleated. The endoplasm contains fat droplets as food vacuoles, contractile vacuoles for osmotic regulation and various vacuoles or crystals containing excretory material. It does not have a definite shape. It constantly produces temporary out-pushings of the cytoplasm called pseudopodia, which are used for locomotion and feeding. Paramecium is aquatic like amoeba. It is seen in fresh water. The body is in the shape of the sole of a slipper. This organism is unicellular but bi nucleated. The large nucleus is called the mega nucleus and the smaller one the micronucleus. The cell is covered with a thin, flexible pellicle. The pellicle is covered with a large number of cilia, which help in locomotion. There are 2 fixed contractile vacuoles at the anterior and posterior end. It takes in food particles from a ciliated shallow depression on the ventral surface called the oral groove, which extends into a narrow tube like gullet.
What is the difference between Algae and Protozoa?
• Protozoans are unicellular, heterotrophic animal like organisms whereas algae are unicellular or multicellular autotrophic plant like organisms.