Main Categories Of Heterotrophic Nutrition Part I

Main Categories Of Heterotrophic Nutrition

                    The   heterotrophic mode of nutrition is found in all animals, Fungi, some protista, many bacteria and some non-green plant like Cuscuta. They consume ready made organic food from other dead or living plant and animals. Therefore, they depend on either autotrophs or other   heterotrophs for their nutrition.

                    When we consider   heterotrophs there are diverse types of organism which depend on a huge variety of food materials. These organisms can be categorized in to three basic groups according to their food type. Now, we shall have a brief idea about the three categories of   heterotrophic nutrition. 

Image : Mode of nutrition of organisms

1. Holozoic nutrition : This mode of nutrition involves the ingestion of liquid or solid organic material. The main steps in holozoic nutrition process include ingestion, digestion, absorption, assimilation and finally ejection. These holozoic animals can be divided in to the three major categories depending on the relative size of the food they intake and their feeding mechanisms, namely Macrophagous feeders, Fluid feeder and Macrophagous feeders.

     2. Saprophytic nutrition :   "Sparos" refers to rotten and 'trophic' refers to food. In this mode of 

         nutrition the organisms feed on dead and decaying organic matter. These organisms secrete   

         digestive juices which contain enzymes to digest the food and then absorb soluble end products 

         into the body.

     3. Symbiotic nutrition :  This is the mode of nutrition in which individuals of two (or more ) 

         different species share their shelter and nutrition. Depending on the degree of benefit and harm, 

         there are 5 types of symbiotic relationships. 

• Mutualism            -  both species benefit
• Commensalism    -   one species benefits, the other is unaffected
• Parasitism            -   one species benefits, the other is harmed 
• Competition         -   neither species benefits
• Neutralism           -   both species are unaffected

Image:   Graphical Representation of the 5 types of symbiotic relationships

         Now you have a brief idea about different types of heterotrophic nutrition. In order to get a broader knowledge about each type in heterotrophic nutrition, Let's have a detailed look to each category.