Marine invertebrates at various trophic levels point at an important role in many ecosystems. Echinoderms (Greek for "spiny skin") is a phylum which contains only marine invertebrates. The adults are recognizable by their radial symmetry (usually five-point) and include starfish, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies. Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone. The phylum contains about 7000 living species, making it the second-largest grouping of deuterostomes (a superphylum), after the chordates (which include the vertebrates, such as birds, fishes, mammals, and reptiles). Echinoderms are unique among
Korarchaeota Korarchaeota In taxonomy, the Korarchaeota are a phylum of the Archaea. The name is derived from the Greek noun koros or kore, meaning "young man" or "young woman," and the Greek adjective archaios which means "ancient." They are also known as Xenarchaeota. Korarchaeota is regarded as a phylum, which itself is part of the archaeal TACK superphylum which encompasses Thaumarchaeota, Aigarchaeota, Crenarchaeota and Korarchaeota. Analysis of their 16S rRNA gene sequences suggests that they are a deeply branching lineage that does not belong to the main archaeal groups, Crenarchaeota and Euryarchaeota. Analysis of the genome of one korarchaeote that was