Mode of Nutrition in Animals 

Introduction

Every activity we perform in a day is possible because of the energy and energy we get from the nutrients and the nutrients we get from the food we eat. 

So here we will discuss the modes of nutrition in animals in brief. Mainly there are two types of modes of nutrition, and they are autotrophic and heterotrophic modes of nutrition. Most of the plants make their food, and they are known as autotrophs. While animals cannot make their food, they are dependent on the plants for food, so they are known as heterotrophs. In a nutshell, the mode of nutrition in plants is autotrophic and in animals is heterotrophic.  

Heterotrophic Nutrition in Animals 

Heterotrophic Nutrition means an organism is dependent on other organisms for food and nutrition. There are various organisms, which cannot make their food, they are known as heterotrophs. This mode of nutrition in animals is known as heterotrophic. 

Example: Fungi, humans, and other animals are directly or indirectly dependent on the plants for food and nutrition requirements. Hence the mode of nutrition in animals is known as heterotrophic Nutrition. 

• Further, there are different types of heterotrophs based on the need of the type of food according to their surroundings, environment, and adaptations
• The heterotrophs, who eat only plants, grasses, shrubs, and saplings are called herbivores. Examples: Cow, Goat, Buffalo, Deer, etc. 
• The heterotrophs who eat other animals are known as carnivores. Example: Lion, Tiger, Leopard, etc. 
• The heterotrophs who eat both plants and animals are called omnivores. Example:  Dogs and Humans
• Further heterotrophs are categorised into different types based on the mode of nutrition. Those categories are Holozoic, Parasites, and saprophytes

Parasitic Mode of Nutrition

It’s a type of heterotrophic mode of nutrition in plants and animals. In this mode, an organism lives on or inside the body of another organism and obtains food and nutrition from the body of the host. The organism that lives on or inside the body and obtains food from other organisms’ bodies is known as a parasite. While the other organism, whose body is used by the parasite, is known as the host. Example: Bedbugs, lice, and tapeworms are parasites. 

• Further, there is a division of parasites based on their mode of nutrition in animals and plants. There are two types of parasites, Ecto and Endoparasites
•  Ectoparasites are those who derive the nutrition from the host body from outside without living inside their body. Example: Ticks and Lice
• Endoparasites are those who live inside the host body and then derive the food. Example: Tapeworm, Ascaris 

Saprophytic Mode of Nutrition

There are various modes of nutrition in animals. but, It is also a mode of Heterotrophic Nutrition. In this mode of nutrition, organisms obtain food from the dead and decaying matter, like an organic matter of dead animals and plants. The organism that obtains food from the saprophytic mode is called saprophytes. Example: Fungi, some protists, bacteria, etc. 

Holozoic Mode of Nutrition

 If we talk about the type of nutrition in humans then it is holozoic nutrition. Humans eat or ingest food and then digest the food for fulfilling the requirements of nutrition, the digested food gets absorbed and assimilated and the waste is excreted out. This type of nutrition is known as holozoic nutrition. 

Autotrophic Mode of Nutrition 

The organisms who can make their food, which is not dependent on any other organisms for fulfilling the requirements of nutrition, are known as autotrophs. Their mode of nutrition is known as autotrophic. Like plants, they make their food by using inorganic materials like water, carbon dioxide, sunlight, and chlorophyll. In simpler words, photosynthesis is used for converting light energy into food. Food is stored in the form of starch within the plants. Example: Plants, Cyanobacteria, and algae are autotrophs. 

• Photosynthesis is categorised into three processes. Absorption, conversion, and reduction are the processes involved in photosynthesis
• Chlorophyll is found in the leaves of plants, so the chlorophyll present in leaves absorbs the sunlight and traps it for the process of photosynthesis and this process is called absorption in photosynthesis
• This light energy is converted into chemical energy and the water molecules dissociate into hydrogen and oxygen molecules. This process is known as conversion in photosynthesis
• In the end, carbon dioxide is reduced and the hydrogen molecules combine with the molecules of carbon present in carbon dioxide to form carbohydrates. This process is known as Reduction in photosynthesis

Conclusion

Nutrition is the requirement of every living organism, but every living organism doesn’t get its nutrition from the same model. Every organism has a different mode of nutrition. So we have discussed the various modes of nutrition in animals above. Except for animals, we have discussed the mode of nutrition in plants also. Plants are autotrophs and animals are considered heterotrophs. Further, there is a division of heterotrophs such as herbivores, carnivores, and omnivores. I have discussed them in brief. The process of photosynthesis is mainly in plants.