What is heterotrophic nutrition? Describe its types.

Heterotrophic nutrition is nutrition obtained by digesting organic compounds.

The four main types of heterotrophic nutrition are:

• Holozoic nutrition: The word holozoic is made from two words- Holo means whole and Zoikos means animals and literally means animals which eat their food whole. Complex food is taken into a specialist digestive system and broken down into small pieces to be absorbed. This consists of 5 stages, ingestion, digestion, absorption, assimilation and egestion. E.g.: human
• Saprobiontic/saprophytic nutrition: Organisms feed on dead organic remains of other organisms. E.g.: decomposers
• Parasitic nutrition: Organisms obtain food from other living organisms (the host), with the host receiving no benefit from the parasite. When a parasite is present inside the body of the host, it is known as an endoparasite. These parasites suck and feed on the blood of the host. E.g.: tapeworms
• Symbiotic nutrition: Two organisms live in close association to benefit each other or one of the two benefits the other whilst it itself suffers neither loss but nor does it gain. E.g.: fungi and algae, rhizobium and leguminous plants roots.