Koalas & their Advanced Digestive Mechanisms

Koalas possess a highly advanced digestive system which works in its own unique way for koalas. Koalas only eat Eucalyptus leaves and these leaves are full of poisons such as the cyanide compounds. On the other hand; these poisons hardly have any adverse effect on koalas as their digestive system is advanced enough to digest the Eucalyptus poisons and also release energy for koalas.

Koalas have a very advanced digestive system which helps it to survive on one of the poisonous foods of Eucalyptus leaves.

A normal herbivore may simply die if it will be fed on the Eucalyptus diet while humans may simply fall ill or even die too merely by taking it in smaller proportions. However; koalas live their entire lifespan on the Eucalyptus leaves and their advanced digestive system holds the key in this regard. Let’s learn further about the digestive system of koalas and explore its key features which make the koalas' digestive system different from others.

Koalas digestive system is advanced enough to help them thrive on the Eucalyptus foliage.
Koalas possess such an advanced digestive system that they thrive throughout their lives on the poisonous Eucalyptus leaves. Photo courtesy of  

Koalas Possess
Highly Advanced Digestive System Koalas only Eat
Eucalyptus Leaves A Normal Herbivore
Will not Survive on Eucalyptus Koalas Advanced Digestive System
Helps Koalas to Thrive on Eucalyptus Foliage

Koalas have advanced digestive Mechanism.
Koalas Digestive Mechanism is highly Advanced. Eucalyptus leaves have very little or no nutritional value. However, Koalas' advanced digestive mechanism helps them to extract useful nutrition. This picture belongs to 

The basic process of the koalas’ digestive system functions in the similar way like the usual digestive system of the other animals (most of them). However; the digestive system of koalas possesses certain specialized mechanisms within it which makes it highly advanced and unique as compared to the other animals.

Koalas digestive system is almost similar to other animals but it is the presence of the special mechanisms within their stomach which help them to extract energy from the Eucalyptus leaves.

Their digestive system is similar in working to other animals because just like all herbivores, koalas first chew their food, pass them to their stomach from where it first goes to the small intestine and then to caecum and finally to the large intestine for excretion. Nevertheless; it is the presence of the specialized mechanisms within different parts of their digestive system which help koalas to produce energy for their bodies.

Koalas digestive system has specialized mechanisms to extract energy from the Eucalyptus foliage.
Koalas' digestive system comprises of specialized mechanisms which help them to extract energy from the notorious Eucalyptus leaves. Photo courtesy of  

Koalas Digestive System is
Similar to Other Herbivores Koalas Digestive System Has
Special Mechanisms to Extract Eucalyptus Energy

Koalas food Digestion within Large Intestine.
Food Digestion within the Koalas take place either at the Stomach or at their hindgut through the process of fermentation. This picture belongs to 

When koalas eat the Eucalyptus leaves through their mouth, the chewed Eucalyptus leaves directly reach their stomach via esophagus pipe. It is believed that koalas extract much of their energy requirements from their stomach. Koalas’ stomach and the small intestine have special cellular contents which help koalas to absorb energy from the chewed leaves.

Koalas’ chewed food is mostly digested from their stomach and the small intestine through special cellular contents. Koalas do not rely much on extracting energy from their hindguts.

However; unlike other animals, koalas do not rely much on bacterial fermentation process within their hindguts despite the fact that koalas have a very large caecum and proximal colon which is also known as the fermentation chamber. Koalas only fulfill less than 10% of their energy requirements through their hindguts.

Most of Koalas' food is digested at the stomach
Most of the koalas' food is digested through its stomach. Koalas' stomach and small intestine have cellular contents which extracts energy. Photo courtesy of  

Koalas' Stomach Extracts
Most of the Eucalyptus Energy Koalas Stomach & Intestine has
Cellular Contents for Extracting Energy Koalas also Extrace Energy
Through Fermentation Koalas' Energy via Fermentation
Less than 10 Percent

Koalas' Food Digestion.
Koalas Food Digestion is a complex process. However, Koalas do possess different advanced enzymes that are helpful in their digestion. This picture belongs to 

According to the koala experts; only the smallest food particles (finely chewed Eucalyptus leaves) are retained by the koalas’ hindgut for the fermentation process. This fermentation process releases very little energy and in the case of the Eucalyptus leaves even lesser amount of energy is produced for koalas from the fermentation chamber.

During the process of digestion, the finely chewed particles are retained within the hindgut of koalas while larger food particles are passed on to the large intestine, where water contents are absorbed.

On the other hand; the larger food particles which are not fit for digestion are passed into the larger intestine from where they finally reach for its excretion outside the body from rectum and anus. Koalas’ large intestine also helps them to absorb water contents as well from the indigestible food.

Only Smallest Food Particles
Produce Energy for Koalas Larger Food particles
Are Excreted via Large Intestine Koalas' Large Intestine
Absorbs Water Conents

Koalas' hindgut only stores finely chewed food particles for the fermentation process.
The koalas' hindgut only stores finely chewed process for the release of energy through the fermentation process. Photo courtesy of 

Another key process that chiefly influences the digestive system of koalas is called merycism. The process is somewhat similar to the rumination process within the herbivore mammals. During this process koalas regurgitate the food contents from their stomach and rechew them as the finely chewed contents. Remember; only properly chewed contents and smallest of particles release energy for koalas during digestion while the bigger food contents are passed on to the larger intestine for excretion.

Merycism is also one of the key processes within the digestive system of koalas. In Merycism koalas regurgitate their food contents and convert them into the smallest finely chewed contents for proper digestion.

The smallest food contents are also retained and stored by koalas within their hindgut for energy (Only 10% of their body energy is retained through hindgut). Therefore; the process of merycism specifically helps koalas to have proper digestion and extract maximum energy from the finely chewed Eucalyptus leaves.

Koalas Digestive System
Also Involves Mercycism Merycism in Koalas is
Similar to Rumination within Herbivores Merycism Helps Koalas
To Finely Chew the Food Particles Merycism also allows Koalas
To Store Food Particles for Fermentation Energy

koalas' digestive process also involves merycism in which they re-chew their food.
Koalas' advanced digestive system also comprises of the process of merycism in which they re-chew the Eucalyptus leaves to convert them into small particles. Photo courtesy of 

If we conclude the overall digestive system of koalas, it looks quite similar to the other animals. However; the ability of this digestive system to extract most of the energy from stomach, the process of merycism and the storage of finely chewed food contents within their hindguts make digestive system of koalas a bit advanced as compared to the other animals.

Even though koalas possess a highly advanced digestive system which helps them to extract energy from the Eucalyptus leaves, they still have to rest more than 20 hours per day to conserve their body energy.

Lastly; the food metabolism of koalas is very slow as compared to the other animals. Lastly; despite the presence of an advanced digestive system, the energy extracted from the Eucalyptus leaves only allow koalas to have an active lifestyle for 3 to 4 hours per day while for almost 20 to 21 hours they mostly sleep to conserve their body energy.

Koalas' Digestive System
Produces Very Little Energy Energy Production is Low
Because of the Eucalyptus Consumption. To Retain their Body Energy
Koalas sleep more than 20 Hours per Day

Koalas digestive system produces little energy for koalas due to the Eucalyptus leaves.
Despite all such advancements of the digestive system of koalas, their digestive system produces very little energy for them. Koalas have to sleep more than 20 hours per day to retain their body energy. Photo courtesy of