DIFFERENT STEPS OF NUTRITION
Ingestion: The act of taking food inside by the organisms is called ingestion.  Most of the animals consume solid food, excepting a few (mosquitoes, flies and spiders suck in liquid food). Different animals use different organs for this purpose. For example Amoeba, a unicellular organism can ingest food from its body surface. In Hydra, the food is taken inside with the help of tentacles. In vertebrates like frogs, birds and mammals, well-developed organs and methods are present to ingest food.

Feeding involves procurement as well as ingestion of food. Depending upon the nature of food, feeding may be of three types in animals.  

Microphagy : This method is also known as filter feeding. Food particles smaller in size pass through filter along with water. The food particles are trapped and utilized whereas water is removed through body. Examples of organisms which show microphagy are paramecium, sponges, crustaceans, certain fishes and birds, blue whales, etc.

Macrophagy : This method involves the feeding of food particles which are large in comparison to the size of the organism. Organisms swallow whole food without chewing. Example of organisms which shows macrophagy are amoeba, hydra, certain amphibians, reptiles, fishes and birds.

Liquid feeding: Leeches, tape-worm, mosquitoes, bugs, spiders, flies, bats and mil-sucking young mammals shows different feeding behaviour where they ingest liquid food, known as liquid feeding or fluid-feeding.
We have listed some mode of feeding that organism exhibits

• Filter feeding: feeding particles suspended in water.
• Deposit feeding: feeding particles suspended in soil.
• Bulk feeding: feeding all of an organism.  
• Fluid feeding: feeding fluid of other organisms.
• Ram feeding and suction feeding: ingesting food particles via the fluids around it.