Figure 1

A simplified view of animal phylogeny, showing the taxonomic position of groups and organisms mentioned in the text (genera are in italics). Taxa above the red line are animals. Relationships among the non-bilaterian phyla remain controversial, but the topology shown reflects the current consensus. Numbers in red are percentages of the total number (2,308) of Pomatoceros ESTs with matches against specific taxonomic groups. Numbers on the boundaries between taxonomic groups are shared exclusively between Pomatoceros and those groups, whereas in the cases of non-bilaterians and bacteria/protists the numbers reflect ESTs shared between Pomatoceros, lophotrochozoans and those taxonomic groups. For example, 7% of Pomatoceros ESTs are shared only with lophotrochozoans and deuterostomes, and less than 1% are shared only with lophotrochozoans and non-bilateral animals or with lophotrochozoans and bacteria or protists. Over half (1,205; 52%) of the total number of Pomatoceros ESTs had no matches in the databases.