Animal

Definition

The term animal is used to refer to any living organism that falls in the animal kingdom, one of the kingdoms in the six-kingdom system of classification of species (the other kingdoms are plants, bacteria, archaea, fungi and protists). The following attributes collectively separate animals from other living organisms:

Attribute	Value for animals	Other kingdoms that share (or may share) this attribute value	Kingdoms that don't share this attribute value
Cell type	eukaryotic cell	plants, fungi, protists	bacteria, archaea
Cell type	does not have a cell wall	some protists (specifically, protozoa)	plants, fungi, bacteria, archaea
Cellularity of organism	multicellular organism	plants, fungi	protists, bacteria, archaea
Mode of nutrition	heterotrophic organism	some plants, some protists	most plants (including algae), fungi
Nature of birth	embryos pass through a blastula stage	none	all other kingdoms

The cells of animals are called animal cells. These differ in many important respects from the cells of organisms in other kingdoms.