Steps of holozoic nutrition:

(1) Ingestion→ It is a process of intake of food materials. In case of holozoic nutrition, food is ingested through mouth.                       

(2) Digestion→ It is a process of conversion of large organic molecules obtained from diet into simpler absorbable forms.

(3) Absorption→ It is process of absorption of digested absorbable form of food through various methods for further use.

(4) Assimilation→ It is a process of utilization of absorbed food to meet energy requirements of body to perform all metabolic functions.

(5) Egestion→ It is the removal of excretory waste materials (faeces, urine) outside of body through excretory organs.

Incomplete digestive system:

Organisms have a single opening which act as both mouth for ingestion & for removal. There is no any different region for storage, digestion or absorption. It is found in annelids, flatworms, arthropods and mollusks.