Nerve net Nerve net A nerve net consists of interconnected neurons lacking a brain or any form of cephalization. While organisms with bilateral body symmetry are normally associated with a central nervous system, organisms with radial symmetry are associated with nerve nets. Nerve nets can be found in members of the Cnidaria, Ctenophora, and Echinodermata phyla, all of which are found in marine environments. Nerve nets can provide animals with the ability to sense objects through the use of the sensory neurons within the nerve net. The nerve net is the simplest form of a nervous system found in multicellular organisms. Unlike
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