Holozoic nutrition is a mode of nutrition in which organisms consume solid or liquid organic food materials and digest them internally. It involves the ingestion, digestion, absorption, and assimilation of complex organic substances to obtain energy and nutrients. This type of nutrition is primarily observed in animals.

The process of holozoic nutrition typically involves the following steps:

1. Ingestion: The organism takes in food through specialized structures such as mouths or feeding appendages. Ingestion can vary depending on the organism’s feeding habits, including predation, herbivory, or omnivory.
2. Digestion: After ingestion, the ingested food is broken down into simpler molecules through mechanical and chemical processes. Mechanical digestion involves physical actions like chewing, grinding, or churning, while chemical digestion involves the use of enzymes to break down complex molecules into smaller units. Digestion can occur in specialized digestive organs or compartments, such as the stomach or intestines.
3. Absorption: Once the food is digested, the resulting nutrients are absorbed into the bloodstream or body cells. This absorption typically takes place in the small intestine, where nutrients such as glucose, amino acids, and fatty acids are absorbed into the bloodstream for distribution throughout the body.
4. Assimilation: In this step, the absorbed nutrients are utilized by cells for energy production, growth, and repair. Nutrients are further metabolized within the cells to release energy through cellular respiration or used to build new cellular components.
5. Egestion: The indigestible waste or undigested materials, such as fiber or undigested food particles, are eliminated from the body as feces. Egestion usually occurs through the rectum and anus.

Holozoic nutrition allows animals to obtain a wide range of nutrients, including carbohydrates, proteins, lipids, vitamins, and minerals, from various food sources. Different animals have adapted to consume specific types of food based on their anatomical structures, feeding behaviors, and digestive systems.

It is important to note that holozoic nutrition is distinct from autotrophic nutrition, where organisms can produce their own food through processes like photosynthesis or chemosynthesis, and from saprophytic nutrition, where organisms obtain nutrients by decomposing and absorbing organic matter from dead organisms or decaying material.