Heterotrophic Nutrition : It is a mode of nutrition in which the organisms obtain readymade organic food from outside sources. The organisms that depend upon outside sources for obtaining organic nutritens are called heterotrophs. Heterotrophic nutrition is of three types - saprophytic, parasitic and holozoic.
Type Of Heterotrophic Nutrition
1. Saprophytic or Saprotrophic Nutrition :
It is a mode of heterotrophic nutrition in which food is obtained from organic remains like dead organisms, excreta, fallen leaves, broken twigs, food articles, etc. Organisms performing saprophytic nutrition are called saprophytes.
2. Parasitic Nutrition :
It is a mode of hetrotrophic nutrition in which a living organisms flourishes by obtaining food from another living organism. The lving organisms which obtains food and shelter from another organism is called parasite. The organism which provides food and shelter to a parasite is known as host. An external plant parasite is Cuscuta (Amarbel). It is a non-green plant that sends haustroria or sucking roots into host plant for obtaining food and water.
3. Holozoic Nutrition :
It is a mode of heterotrophic nutrition which involves intake of solid pieces of food. Since solid food is taken in, holozoic nutrition is also called ingestive nutrition. The food may consist of another animal, plant or its parts. Depending upon the source of food, holozoic organisms are of three types – Herbivores, carnivores, omnivores.