Nutrition in Animals

Animals obtain their food from either plants , or other animals , since they cannot synthesize their own food.

Animals use the method of digestion to break down the complex organic material that they take in externally. This food is broken down into smaller molecules inside the body, which then is used to carry out the various body functions.

They can be divided into 3 groups based on their food habits:

1. Herbivores
2. Carnivores
3. Omnivores

• Herbivores 

Animals that eat only plants are called Herbivores.

        Eg.: Cows, goat, buffalo, monkey

•  Carnivores

Animals that only eat other animals are called Carnivores

       Eg.: tiger, lion, vulture, lizards, snakes

• Omnivores

Animals that eat both, plants and other animals , are known as Omnivores.

                  Eg.: Humans, dogs, crow, bear, ant

Nutrition in Amoeba

Amoeba is a unicellular animal that lives in water. It eats microscopic plants/animals floating in its surroundings. This mode of nutrition is called Holozoic nutrition..The process of obtaining food by an amoeba (or any unicellular organism) is called phagocytosis .

• Ingestion:

• An amoeba does not have a mouth. It ingests food using its pseudopodia .
• Pseudopodia are temporary figure like projections. 
• They engulf the food particle with some water to form a vacuole .

• Digestion:

• It releases digestive enzymes in the vacuole which break down food into small, soluble molecules.

• Absorption:

• This digested food is absorbed into cytoplasm by diffusion. After diffusion, the food vacuole disappears. 

• Assimilation:

• The energy obtained from the food is used for the growth and development of amoeba and this is known as assimilation.

• Egestion:

• When a considerable amount of undigested food accumulates inside the amoeba, it’s cell membrane ruptures and the waste is discarded

Nutrition in Paramecium 

Paramecium is also a unicellular organism that lives in water. 

• Ingestion:

• Paramecium has hair-like structures called cillia that it uses to sweep food particles from water and put them into its mouth .
• The cilia move back and forth to move the food particle towards the mouth. The process is known as ingestion . 

• Digestion:

• It releases digestive enzymes in the vacuole which break down food into small, soluble molecules.

• Absorption

• This digested food is absorbed into cytoplasm by diffusion. After diffusion, the food vacuole disappears. 

• Assimilation:

• The energy obtained from the food is used for the growth and development of amoeba and this is known as assimilation.

• Egestion:

When a considerable amount of undigested food accumulates inside the amoeba, it’s cell membrane ruptures and the waste is discarded

In multicellular organisms, the similar  digestive processes are carried out by a combination of digestive organs.This group of organs is called the Digestive System .