Multicellular organisms excludes all animals.
Multicellular organisms are organisms that consist of more than one cell , in contrast to unicellular organisms .. cell. cell ( biology ). All species of animals , land plants and most fungi are multicellular , as are many algae , whereas a few organisms are partially uni - and partially multicellular , like slime molds and social amoebae such as the genus Dictyostelium .. land plants. Embryophyte. fungi. fungi. algae. algae. Dictyostelium. Dictyostelium. Multicellular organisms arise in various different ways , for example by cell division or by aggregation of many single cells .. cell. cell ( biology ). cell division. cell division. Colonial organisms are the result of many identical individuals joining together to form a colony .. colony. colony ( biology ). However , it can often be hard to separate colonial protists from true multicellular organisms , because the two concepts are not distinct ; colonial protists have been dubbed `` pluricellular '' rather than `` multicellular '' .