Nutrition in Animals

Nutrition is a factor that is important for all living beings. For animals and plants also, it is important for their survival. Through the process of photosynthesis, plants prepare their own food but animals cannot prepare their food and therefore are dependent on plants or other animals for their food. 

Animals fulfill their nutritional needs either by eating plants directly (herbivores) or indirectly by eating animals that have consumed plants (carnivores). Animals that depend on both plants and animals; are termed as omnivores.  For proper growth and survival, all the organisms require food irrespective of the source they derive from their food. 

Food has different components, called nutrients, like carbohydrates, fats, minerals, proteins, and vitamins, which are required for the maintenance of the body. These components are complex and cannot be used directly, so they are broken down into simpler components by the process of digestion.

Feeding Habits of Animals

Feeding habits of animals provide them their adequate nutrition which they intake by the process called Ingestion. The method of ingestion differs in different animals. For example- Nectar is the source of food for bees and hummingbirds, python tends to swallow its prey, and the grass is being ingested by cattle. 

Different feeding habits of animals lead to an Evolution. The earliest forms were large amphibians that ate fish among the terrestrial animals. While amphibians like frogs fed on small fish and insects, the reptiles began feeding on other animals and plants.

Evolution of form and function is caused by the specialization of organisms towards specific food sources and of course specific ways of eating. 

For instance, the difference in mouthparts and teeth in whales, mosquitos, tigers, and sharks or distinct forms of beaks in birds, such as in hawks, woodpeckers, pelicans, hummingbirds, and parrots are a perfect example of adaptation to different types of eating by these animals.

Animals can be divided into the following groups depending upon their food habits:

Herbivores: Animals that depend upon plants and fruits for their nutrition are called Herbivores. Cows, goats, sheep, buffaloes, etc. are herbivores.

Carnivores: Carnivores are animals that depend upon other animals for food. Lion, tigers, wolfs are some of the carnivores.

Omnivores: These include organisms that eat both plants and animals. Humans, bear, dogs, crow are omnivores.

Types of Nutrition  in Animals

The different types of nutrition in animals include:

• Filter Feeding: It is a process of acquiring nutrients from particles suspended in water. This method is commonly used by fish.

• Deposit feeding: It is the process of obtaining nutrients from particles suspended in the soil. Earthworms use this method to take nutrition. 

• Fluid feeding:  When one animal obtains nutrients by consuming other organisms’ fluids. Honey bees, mosquitos follow this mode of food intake.

• Bulk feeding: Eating whole organisms and grabbing nutrients from it. 

• Ram feeding and suction feeding: Consuming prey as food via the fluids around it. This mode of ingestion is usually adopted by aquatic animals such as bony fish.

Process of Nutrition in Animals

The process of nutrition in animals are as follows - 

• Ingestion

Ingestion is the process of taking in food.

• Digestion

In this process, the larger food particles are broken down into smaller, water-soluble particles.  There are physical or chemical for digesting food.

• Absorption

The digested food is absorbed in the bloodstream through the intestinal wall.

• Assimilation

The absorbed food is used for energy, growth and repair of the cells of the body.

• Egestion

The undigested food is removed out of the body in the faeces. This process is known as egestion.

Nutrition in Simple Animals

Amoeba

• Amoeba ingests its food with the help of pseudopodia.

• The food is engulfed by forming a vacuole and is digested with the help of digestive enzymes.

• The digested food is absorbed directly into the cytoplasm by the process of diffusion.

• Energy is obtained from the absorbed food that helps in its growth.

• The undigested food is egested out of the body of amoeba by rupturing the cell wall.