Difference Between Egestion and Excretion (With Table)

The human body is a complex system. Cells come together to form Tissues; Tissues form Organs, and the Organs altogether form the Organ System. The Organ System is the basis of every process that takes place in the body. The Organ System is divided into 12 major systems that collectively take care of bodily functions. Digestive System and Excretory System are two of the major systems.

Egestion vs Excretion

The difference between Egestion and Excretion is that Egestion is the process of removal of undigested food particles from the body, whereas, Excretion is the process of release of metabolic wastes from the body. Egestion comes under the function of the Digestive System, while Excretion comes under the function of the Excretory System.

Egestion is the process of removal of the undigested food from the body through the anus. The food which could not be digested in the process of digestion comes out through Egestion. Sometimes, the undigested food is released out through the mouth instead of the anus. This takes place in rare situations only. The process of egestion occurs only in animals.

On the other hand, Excretion is the process of elimination of metabolic wastes from the cells of the body. The toxins or waste products are filtered out from the cells by this process. It occurs in both plants and animals. The wastes are released through the kidneys, lungs, skin etc. Excretion helps in keeping the cells clean and free from toxicity.

Comparison Table Between Egestion and Excretion

Parameters of ComparisonEgestionExcretion
DefinitionEgestion is the removal of undigested food from the body.Excretion is the release of wastes from the body.
Type of WasteUndigested food and other toxins left after digestion. Metabolic wastes including carbon dioxide, sweat etc.
Occurs inIt occurs only in animals. It occurs in plants as well as animals.
OrgansIt usually occurs through the anus and, rarely, the mouth. It occurs through kidneys, lungs, skin.
Materials ReleasedThe faeces are released through egestion. Sweat, urine, carbon dioxide are released through excretion.
SystemEgestion is a part of the digestion process. Excretion is the main function of the excretory system.
SignificanceIt completes the process of digestion. It keeps the cells of the body clean.

What is Egestion?

The body could not function without the list of life processes that take place within. These processes are grouped under major systems of the body. The Digestive System is one such major system of the body. Its primary function is digestion. Digestion is carried out in certain steps, and Egestion is one of them.

Some of the food particles and other materials do not get digested during the process of digestion. This undigested food is then removed from the body through the anus or, sometimes, the mouth, which completes the digestion process. This process of release of the undigested food is known as Egestion. It occurs only in animals, not in plants.

The food substances that are released out during egestion are termed faeces. First of all, the undigested food is pushed towards the rectum through muscular contractions. Temporarily, the faeces get stored there. With the accumulation of more and more faecal matter, the rectal walls tend to expand, which results in the need to release out the faeces. If not acted upon, the faeces return to the colon for water absorption once again.

The next wave of contractions results in the final elimination of the faeces out of the body through the anus. Egestion rarely occurs through the mouth while vomiting. Constipation and Diarrhoea are the disorders of Egestion. Delay in the process causes Constipation, whereas a faster egestion where the food contains excess water causes Diarrhoea.

What is Excretion?

The excretory system is as important to the body as the digestive system. Digestive System digests the food in the body, while the Excretory System excretes the waste materials from the body in various forms. Excretion is the primary function of the Excretory System. It occurs in both plants and animals.

During life processes, a number of chemical reactions occur in the body. These are termed metabolism. These reactions produce wastes in the form of water, carbon dioxide, salts, uric acid and urea. These wastes are called metabolic wastes. These are released out from the body by the excretory organs. This process of release of the metabolic wastes is known as Excretion.

In unicellular organisms, excretion takes place directly through the cell surface. In other words, the toxins are released through the cells directly. Whereas in vertebrates, the organs, i.e. lungs, kidneys and skin, help in carrying out the process of excretion. The waste products come out in the form of sweat through the skin, while the kidneys filter out the wastes in the form of urine and urea.

In green plants, oxygen and excess water are released out through excretion. Excretion is equally essential for both plants and animals. It helps in keeping the cells of the body toxin-free and maintains bodily balance.

Main Differences Between Egestion and Excretion

  1. Egestion is the removal of undigested food, while Excretion is the removal of metabolic wastes.
  2. Digestive System controls egestion, whereas, Excretory System controls excretion.
  3. Egestion occurs only in animals, but Excretion occurs in both plants and animals.
  4. Sweat, urea, carbon dioxide etc., are removed by excretion, while faeces are removed by egestion.
  5. Egestion occurs through the anus and mouth, while Excretion occurs through kidneys, lungs etc.


Life processes are the basis of the body. These control everything that goes on within the body. The processes are categorised under various body systems. Each system has its assigned function, which occurs one after the other.

Egestion and Excretion are two of the most important life processes that take place in the body. Egestion is a part of the Digestive System, while Excretion is a part of the Excretory System. Both the processes are related to the removal of waste materials and toxins from the body.

The bodily functions are maintained by these processes. The undigested food gets released out by egestion. In contrast, the metabolic wastes are removed by excretion.


  1. https://www.mdpi.com/546508
  2. https://www.cambridge.org/core/journals/journal-of-the-marine-biological-association-of-the-united-kingdom/article/feeding-respiration-and-excretion-by-the-tropical-sea-urchin-tripneustes-gratilla-echinodermata-echinoidea-from-the-philippines/1DA459664848EE89E34971321952A487
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