This tree diagram shows the relationships between several groups of organisms.
You can click on the root to travel down the Tree of Life all the way to the root of all Life, and you can click on the names of descendent subgroups to travel up the Tree of Life all the way to individual species.
For more information on To L tree formatting, please see Interpreting the Tree or Classification.
To learn more about phylogenetic trees, please visit our Phylogenetic Biology pages.
Figure 1: Summary of phylogenetic hypothesis in Rouse and Pleijel (2001). The phylogenetic position of Brachiopoda- a comparison of morphological and molecular data.
Moreover, it is possible that this group may well belong inside Polychaeta, thus making Polychaeta synonymous with Annelida (Mc Hugh, 1997; Westheide, 1997; Westheide et al., 1999).
Echiura (spoon worms), at one time regarded as an annelid group (Sedgwick, 1898), has been excluded from Annelida for many years (Newby, 1940). Evidence now suggests they are in fact annelids (Hessling and Westheide, 2002; Mc Hugh, 1997), though their placement within the group is unresolved. The former phyla Pogonophora and Vestimentifera have also recently become regarded as a single, clearly annelid, group (Bartolomaeus, 1995; Nielsen, 1995; Rouse and Fauchald, 1995), and are now known by the original name, Siboglinidae (see Rouse and Fauchald , 1997 and Mc Hugh 1997). Alternative arrangements are discussed in the Discussion of Phylogenetic Relationships. The position of Clitellata/Oligochaeta (includes earthworms and leeches) and Echiura is yet to be resolved. Annelida is a group commonly referred to as segmented worms, and they are found worldwide from the deepest marine sediments to the soils in our city parks and yards.