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
Chloroflexi (phylum) Chloroflexi (phylum) The Chloroflexi or Chlorobacteria are a phylum of bacteria containing isolates with a diversity of phenotypes including members that are aerobic thermophiles, which use oxygen and grow well in high temperatures, anoxygenic phototrophs, which use light for photosynthesis (green non-sulfur bacteria), and anaerobic halorespirers, which uses halogenated organics (such as the toxic chlorinated ethenes and polychlorinated biphenyls) as electron acceptors. Most bacteria, in terms of diversity, are diderms and stain Gram negative, notable exceptions being "Firmicutes" (low CG Gram positives), "Actinobacteria" (high CG gram positives) and the "Deinococcus–Thermus" group (Gram positive, but diderms with thick peptidoglycan). In contrast,