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
Ferreira's spiny tree-rat Ferreira's spiny tree-rat Ferreira's spiny tree-rat, "Mesomys hispidus", is a spiny rat species from South America. It is found in Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname and Venezuela. The etymology of the species name corresponds to the Latin word "" meaning "bristly". The description of "Mesomys hispidus" was conducted on a specimen collected by the naturalist Alexandre Rodrigues Ferreira during his travels in Amazonian Brazil, hence the species name. Initially deposited in the Museu Real d'Ajuda of Portugal, it has been brought to Paris in 1808 after the plundering of Lisbon by the armies of Napoleon. Then,