Metazoa

Article By:

Giribet, Gonzalo Harvard University, Cambridge, Masachusetts.

Last reviewed:January 2020

DOI:https://doi.org/10.1036/1097-8542.420300

The monophyletic group of eukaryotic organisms comprising all multicellular animals, but not those in which their cells form colonies, such as choanoflagellates. In colonies, all the cells need to feed because they are not in contact with each other, such that nutrients cannot be transported between them. In multicellular organisms, cells are engaged in a more specialized division of labor because nutrients can be transported between them. Therefore metazoans have specific characters related to cell recognition, adhesion, communication, and skeletal elements responsible for maintenance of the shape of the whole body and its organs. The need for cell-to-cell communication via neurotransmitters evolved into one of the most intriguing systems in all organisms, the nervous system. Other specific characteristics of metazoans are connected to sexual reproduction, such as the origin and structure of haploid gametes, fertilization, and development from the zygote to the adult organism. For most recent authors, Metazoa is a synonym of Animalia.

The content above is only an excerpt.