Changes

Biologically, an animal is any member of the Animalia kingdom. Animals must eat [[plant]]s or other organisms to survive. The plants are called "producers" and the animals are "consumers". Scientists call consumers [[heterotroph]]s. Animals have complex [[eukaryote|eukaryotic]] cells, unlike bacteria which have much simpler [[prokaryote|prokaryotic]] cells.  Animal cells do not have [[cell wall]]s, only structural [[protein]]s in the [[cell membrane]]; this allows the animal cell a certain amount of flexiblity.

Biologically, an animal is any member of the Animalia kingdom. Animals must eat [[plant]]s or other organisms to survive. The plants are called "producers" and the animals are "consumers". Scientists call consumers [[heterotroph]]s. Animals have complex [[eukaryotic cell]]s, unlike bacteria which have much simpler [[prokaryote|prokaryotic]] cells.  Animal cells do not have [[cell wall]]s, only structural [[protein]]s in the [[cell membrane]]; this allows the animal cell a certain amount of flexiblity.

Animals [[evolution|evolved]] from single-celled, colonial protists called [[choanoflagellate]]s.  The simplest of all animals are [[sponge]]s, which do not move, and are instead sessile.  Sponges have different cells for different tasks, but these cells are not organised further into tissues or organs.  Sponges also do not exhibit symmetry, a characteristic found in all other animals.

Animals [[evolution|evolved]] from single-celled, colonial protists called [[choanoflagellate]]s.  The simplest of all animals are [[sponge]]s, which do not move, and are instead sessile.  Sponges have different cells for different tasks, but these cells are not organised further into tissues or organs.  Sponges also do not exhibit symmetry, a characteristic found in all other animals.