Final answer:
Grantia is characterized as an animal because it is eukaryotic, multicellular, heterotrophic, has specialized tissues, is motile during some life stages, and has a fixed body plan following sexual reproduction.
Step-by-step explanation:
Grantia, like all members of the animal kingdom, displays several features that distinguish it from organisms in other kingdoms.
These distinguishing characteristics of Grantia include being eukaryotic, multicellular, and heterotrophic. Unlike autotrophic organisms, Grantia and other animals must ingest other living or dead organisms to obtain nutrients, categorizing them as heterotrophs, which may be carnivores, herbivores, omnivores, or parasites.
Another critical feature is the presence of differentiated and specialized tissues, which are common to nearly all animals but not to most plants or fungi. This sophisticated tissue structure includes nervous, muscular, connective, and epithelial tissues.
Additionally, most animals, including Grantia, are motile during at least some stage of their life. Furthermore, their sexual reproduction and development usually result in a fixed and determined body plan, unlike the indeterminate growth patterns found in many plants.
All these attributes are important in distinguishing Grantia and indeed all animals, from other life forms, highlighting their unique place in the biological classification system.