NUTRITION OF PROTOZOA

NUTRITION OF PROTOZOA

·       Protozoa are Heterotrophic and usually require their food in a complex organic form.

·   Most protozoa are Chemoheterotrophic. They obtain nutrients by phagocytizing bacteria, decayed organic matter, other protozoa, or the tissues of a host; a few protozoa absorb nutrients from the surrounding water.

·       Protozoa nutrition are of three types

a)     Holophytic Protozoa

b)     Holozoic (Phagotrophic) Protozoa

c)     Saprozoic Protozoa

d)     Mixotrophic Protozoa

 

a) Holophytic Protozoa

·  Holophytic Protozoa are those synthesize carbohydrate with the help of Chlorophyll carried in Chromatophores and in the presence of light.

·       Holophytic Protozoa are Photosynthetic protozoa (Example - Phytoflagellates).

·   Phytoflagellates are member of a group of Flagellate protozoans that have many characteristics in common with typical Algae. Phytoflagellates may obtain nutrients by Photosynthesis, by absorption through the body surface, or by ingestion of food particles.

b) Holozoic Protozoa

·      In Holozoic nutrition, solid nutrients such as bacteria are acquired by Phagocytosis and the subsequent formation of phagocytic vacuoles.

·   Holozoic protozoa utilized preformed food material either by Pseudopodia or through a permanent opening called Cytostome. Pseudopodia encircle solid particles and enclose them in the cytoplasm inside food vacuoles into which digestive enzyme secreted.

c) Saprozoic Protozoa

·       In Saprozoic nutrition, soluble nutrients such as amino acids and sugars cross the Plasma membrane by Endocytosis, Diffusion, or Carrier-mediated transport (Facilitated diffusion or Active transport).

·  The mechanisms by which soluble nutrients are assimilated are sometimes collectively called Osmotrophy.

d) Mixotrophic Protozoa

·      Certain Protozoa can derive energy through the oxidation of inorganic substrates but assimilate organic carbon compounds.

·      Some simultaneously use both organic and inorganic forms of carbon. This is sometimes referred to as Mixotrophy.

·   Mixotrophic metabolic flexibility is clearly evident in those forms like the dinoflagellates that can perform photosynthesis and holozoic feeding concurrently.