Metazoa: Systematics

Move deeper into the systematics of metazoan groups by choosing one of the boxes containing a picture!

"Why do evolutionary biologists care who's related to whom,
and how do scientists find out how different animals are related?"

Many scientists have worked on resolving the evolutionary relationships among the major groups of animals. Until recently, these studies have relied upon morphological characters, especially those expressed in early development (e.g. embryological characters). As it turns out, molecules in the cells of animals also contain a great deal of historical information. Therefore, cladistic studies of phylogenetic relationships that rely upon the information stored in molecules have become increasingly common. The phylogeny presented here is based upon various published studies of 18S ribosomal RNA sequences and was compiled by Dr. James W. Valentine.

Visit the Tree of Life for more information concerning the systematics of animals.

For some classic images of invertebrate animals and protists, created in the 19th century by the great zoologist Rudolph Leuckart, click here to visit the Marine Biological Laboratory at Woods Hole, Massachusetts.