Multicellular organisms are those composed by multiple cells. They are classified in 13 major groups of terrestrial living beings, including animals, plants, fungi, ciliates, algae, and foraminifera. The number of cells per organism range from some tens to up to several million. The cells in a multicellular organism are usually varied, differentiated, and specialized.
The evolutive path toward multicellularity seems to be not particularly challenging, as different groups of multicellular organisms seem to have evolved independently (Rokas 2008). Also, it is possible to follow the invention of multicellularity in separate major clusters of organisms within the 13 main groups, as they are well known to be polyphyletic. In general, aquatic organisms became multicellular because the daughter cells did not separate completely during cell division, while land multicellular organisms formed by the aggregation of a...
KeywordsAtmospheric oxygen Body size Cambrian Ediacara Multicellular Paleoproterozoic Specialization
References and Further Reading
- Smith JM, Szathmáry E (1997) The major transitions in evolution. Oxford University Press, New YorkGoogle Scholar