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Define Egestion and Excretion with Examples

Food is the prime part of a living organism’s life. Collecting food or preparing them with the resources available is done every day for survival. Every organism that ingests food also must have a way to reject the unused, undigested, and unassimilated food particles. This process is called excretion. In this section, we will learn what egestion is and how it is a type of excretion. The egestion meaning and operations vary from one species to the other. Let us find out the meaning of excretion and egestion to understand the differences between them.

What is Excretion?

Excretion is the final part of the metabolism of an organism where the ingested food is being digested, absorbed, and assimilated and the waste material or by-products are eliminated through a particular set of organ systems. When a plant prepares its own food via photosynthesis or breaks it down, it produces by-products that need to be eliminated. The process of the removal of those by-products or food remnants is called excretion.

Now that you have understood what excretion is, you can easily realize that egestion is a type of excretion where cells and unicellular animals get rid of unwanted food particles or by-products of digestion. Let us proceed further and find out the egestion meaning.

What is Egestion?

The process by which unicellular organisms such as an amoeba excrete or eliminate unwanted particles, undigested food, or anything toxic by using the mechanism of the formation of food sacs or vacuoles is called egestion. It is a very fascinating fact that the flexible food sacs or vacuoles form around any ingested food in an amoeba. The digestive enzymes are then released inside these sacs resulting in the slow digestion of the food particles. When the digestion is almost over, they reach the extreme periphery of the protoplasm.

These sacs then merge with the cell membrane in such a way that a channel is produced in them. The sac then gradually assimilates with the cell membrane and throws out the content. This is how you can describe what is egestion.

As per the egestion definition biology, it happens in the complex species as well. The terms excretion and egestion are so close in meaning that they can be replaced in different situations. Peristaltic movement in the large intestine of mammals helps in excreting the undigested food from the body. It can also be called elimination.

Let us consider an example. An amoeba engulfs an organism with the help of its pseudopodia. The engulfed food forms a vacuole or a food sac. This sac is ten exposed to digestive enzymes secreted by the organelles. The enzymes then digest the food inside into smaller units and prepare the food for assimilation. After the process of intracellular digestion and assimilation, the leftover undigested food particles remain in the sac.

The sac then proceeds towards the periphery and gets attached to the cell membrane. The food sac then loses its area and assimilates entirely with the membrane thus releasing the unwanted food particles outside. This is how you can define egestion.

Difference between Excretion and Egestion

If you observe the terms carefully, you will find their differences easily. Both refer to the physiological act of eliminating the waste products from the system. As per the literal meaning of the terms, both mean the elimination of undigested or waste products from a cell or a body. Despite the fact, there is a slight difference between excretion and egestion. In this section, we will study it elaborately.

  • Egestion is the process of undigested food particles from a complex anatomical system or a unicellular organism. Excretion, on the other hand, is the process of removal of by-products from the cells in a multicellular organism.

  • The content lost via the end of the digestive tract of an organism is undigested food particles. These undigested particles are the leftover of an elaborate digestion process ending in egestion. In excretion, the by-products of cellular metabolism are eliminated via sweat, urine, etc. Plants losing leaves and getting rid of metabolic by-products are also an example of excretion. Egestion and excretion differ in the content eliminated.

  • Egestion happens through the anus. Excretion occurs from the skin, kidney, and nose.

  • Egestion is witnessed in complex animals that have a mouth and an anus. Excretion, on the contrary, happens in plants and animals.


Now that you have understood how egestion occurs, you can easily differentiate between it and excretion. It is easier to understand the difference between both terms by using proper examples. Learn what these terms mean and understand the example of egestion in amoeba. It will become a lot easier to answer the questions related to these terms with proper examples.

FAQ (Frequently Asked Questions)

1.  What is the basic difference between Excretion and Egestion?

Ans: The basic difference between egestion and excretion is the elimination of content. Egestion is the last process of digestion. Excretion is the final process of metabolism. If you check the content eliminated then excretory substances are urine, sweat, carbon dioxide, oxygen, etc. The egested substances are leftover of a digestion process.

2.  How can you Compare Egestion and Excretion?

Ans: The easiest way to answer questions related to egestion vs excretion is the analysis of the entire process. Find out which one is the end step of what process. Learn where egestion occurs with example and do the same for excretion. You will easily figure out the differences and compare them easily. Do not forget to use examples.

3.  How can Identify whether a Process is an Egestion or Excretion?

Ans: Understand the basic difference between digestion and metabolism. Metabolism is a cellular activity whereas digestion is a function of an organ system. In metabolism, by-products will have to be collected from all the cells and then eliminated. In digestion, the ingested food travels from mouth to anus and then the leftover is egested through the anus. Egestion happens in animals but excretion happens in plants and animals as it is a part of metabolism.