What type of organisms are included in the kingdom Animalia?

The kingdom Animalia is characterized primarily by multicellular organisms that are heterotrophic, meaning they obtain their nutrients by capturing and digesting other organisms, whether they be plants, animals, or other organic material. This feeding strategy distinguishes animals from other kingdoms such as Plantae, where organisms can produce their own food through photosynthesis, or Fungi, where organisms absorb nutrients from their environment.

Animals generally exhibit a range of complexities in their body structure and function, including various organs and systems for digesting food, which is essential for providing energy and nutrients necessary for growth, development, and maintenance. Furthermore, the ability to move, at least at some stage of their life cycle, and the presence of specialized sensory organs are other distinctive features of multicellular organisms within the kingdom Animalia.

In contrast, unicellular organisms that perform photosynthesis belong to the kingdoms like Plantae or certain groups of Protista. Organisms that absorb nutrients from their surroundings, like fungi, are classified in a different kingdom and do not feed by ingestion. While multicellular organisms that reproduce asexually may exist within the Animalia kingdom, this characteristic alone is not defining as many animals reproduce sexually as well. Thus, the defining feature of capturing and digesting food is