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
Western Saharan spiny mouse Formerly considered conspecific with Cairo spiny mouse "Acomys cahirinus" but there are differences in the number of chromosomes. It may be conspecific with Chudeau's spiny mouse "Acomys chudeaui" from Morocco and, if that is the case, then the correct species name is "Acomys chudeaui" as this name has precedence. Western Saharan spiny mouse The Western Saharan spiny mouse or Aïr spiny mouse ("Acomys airensis") is a species of small, insectivorous rodent in the family Muridae found arid regions of western Africa. The Western Saharan spiny mouse is a small mouse with large ears, small eyes and a sharp snout. The