What is heterotrophic nutrition?
It is the mode of nutrition in which an organism cannot make its own food from simple organic materials and depends on other organisms for its food.
All the animals have a heterotrophic mode of nutrition. Most bacteria and fungi also have heterotrophic modes of nutrition.
The organisms having heterotrophic modes of nutrition are called heterotrophs.
Heterotrophs obtain energy from organic molecules already produced by the autotrophs.
The heterotrophic forms of Nutrition differ in various organisms depending on the type availability and process of obtaining food material by an organism.
Accordingly heterotrophs there are
Types of heterotrophic Nutrition
Heterotrophs can obtain its food from other organisms in three ways. So the heterotrophic mode of nutrition is of three main types
- Holozoic nutrition is nutrition in which an organism takes the complex organic food material into its body by the process of ingestion.
- The ingested food is digested(the complex food molecules are taken in and then broken down into simpler and soluble molecules) and then absorbed into the body cells of the organism.
- The undigested and can absorb part of the food is thrown out of the body of the organism by the process of egestion.
- Types of holozoic Nutrition
- Herbivores-organisms that feed on plants.
- Carnivores-organisms that feed on other organisms.
- Omnivores-organisms that feed on both plants and other animals.
- Example human beings, cats, dogs, cows, goats, amoeba , paramecium etc. have the holozoic mode of nutrition.
Saprotrophic nutrition/ Saprophytic nutrition
- Saprotrophic nutrition is the type of nutrition in which organisms obtain their food from decaying organic matter of dead organisms.
- The organisms having saprotrophic mode of nutrition are called saprophytes.
- Saprophytes break down complex organic molecules present in dead and decaying matter and convert them into simpler substances outside their body. The simpler substances are then absorbed by saprophytes as their food.
- Example fungi like bread moulds mushrooms, yeast and bacteria.
- Parasitic nutrition is the type of Nutrition in which an organism obtains its nutrition from the body of another living organism without killing them.
- The organisms which obtains their food from parasitic nutrition are called as parasites
- The organisms on which parasites depend for their nutrition are called hosts.
- Parasites live either on or inside the body of other organisms to obtain their nutrition without killing them.
- Parasites are dependent upon their host and for that they have considerable modification to optimize parasitic nutrition and therefore their survival.
- Parasites get its nutrition from the host but give no benefit to the host in return. Parasites usually harm the host.
- Most of the diseases which affect human beings, animals and plants are caused by parasites.
- Example plasmodium ticks lice leech tapeworm flatworm plants like cuscuta etc.