It is the process by which an organism obtain its nourishment, the supply of nutrients required by its body and cells to stay alive.

Types: Autotrophic nutrition and Heterotrophic nutrition

Ecology Species, communities and ecosystems - Ms. Frost A world of biology .....

Autotrophic Nutrition:

  • Plant exhibit autotrophic mode
  • They prepare their own food by the process of photosynthesis
  • Also called self-nourishment
  • These are of two types:  
  • Photosynthesis

6 CO2 + 6H2O                                C6H12O6 + 6O2

                        Radiant energy

                        Of sunlight and


Occurs in all green plants

  • Chemosynthesis

CO2 +H20                            CARBOHYDRATES

               Chemical nutrients

Sunlight is not used as an energy source

Used for energy in photosynthesis.

Heterotrophic Nutrition:

  • Animals exhibit heterotrophic mode
  • These are directly or indirectly dependent upon the autotrophs for their organic food
  • They have no chlorophyll  so these cannot trap the radiant energy of sunlight
  • Types:
  • Holozoic or helotrophic

Organism takes in whole food, i.e., whole plant or whole animal or their parts. The food ingested undergoes digestion, absorption and assimilation.

e.g.: small organisms like Amoeba and large organism like Human beings.

Depending upon source of food, they are differentiated into:

  • Herbivores : Plant feeding. Example: Cow, Horse.
  • Carnivorous: meat or animal eaters. Example: Lion, Tiger.
  • Omnivorous: both plant and animal eaters. Example: Cockroach
  • Cannibals: eat upon the member of their own species. Example: Snakes.
  • Detritivores: feed upon dead organic matter in mud. Example: Earthworms.
  • Predators: larger animal feed upon the smaller animal. Example: Eagle, kite.
  • Insectivores: feed upon insects. Example: Frog, Lizards.
  • Edentulous: ant-eaters. Example: Manis, Spiny ant-eater.
  • Scavengers: feed upon dead and decaying animal or plant. Example: Vultures, Crow.
  • Piscivorous: animals feeding upon fish. Example: Crocodiles.
  • Grainivores: herbivores which feed upon the grains. Example: Rock pigeon.
  • Saprophytic Nutrition

Organisms derive its nourishment from dead and decaying matter by releasing enzymes to digest the dead organic food and then the nutrients are absorbed through body surface.

Example: Fungi

  • Osmotrophic Nutrition

Animals take predigested food materials by diffusion through their body wall. Example: Taenia solium

  • Parasitic

Organism derives its nourishment from host organism either in liquid or solid form. Example: Taenia solium is a tape worm living in human intestine.

Types: Endoparasites: live inside the body of the host. Example: Taenia solium, Plasmodium vivax.

Ectoparasites: live in the outer surface of host and generally attach themselves during feeding. Example: Mosquitoes, lice, Bed bugs.

On the basis of foods size, animals are divides into:

Microphagous: animals take small sized food particles. Example: Earthworms.

If food is ingested in liquid form, called fluid-feeders. Example: Mosquitoes.

Macrophagous: animals take food from outside in form of large pieces. Example: Hydra.