Animal mesoderm forms by enterocoelic pouching, through invagination of the endoderm. The main deuterostome phyla are the Echinodermata and the Chordata. Echinoderms are exclusively marine and include starfish, sea urchins, and sea cucumbers. The chordates are dominated by the vertebrates (animals with backbones), which consist of fishes, amphibians, reptiles, birds, and mammals. The deuterostomes also include the Hemichordata (acorn worms). The Ecdysozoa are protostomes, named after their shared trait of ecdysis, growth by moulting. They include the largest animal phylum, the Arthropoda, which contains insects, spiders, crabs, and their kin. All of these have a body divided into repeating segments, typically
Branching order of bacterial phyla (Ciccarelli et al., 2006) Branching order of bacterial phyla (Ciccarelli et al., 2006) There are several models of the Branching order of bacterial phyla, one of these was proposed in 2006 by Ciccarelli "et al." for their iTOL project. This tree is based on a concatenated set of conserved protein and not 16S rRNA (cf. Branching order of bacterial phyla (Woese, 1987)). The arrangement of the various phyla differs from that of 16S, but may be due to long branch attraction and due to the limited sampling (many phyla have a sole sequenced representative, whereas the Firmicutes and the Proteobacteria are over-represented). The Proteobacteria