Marine life individuals per square meter and accounting for about 80% of all individual animals on earth, their diversity of life cycles, and their presence 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
Tuft-tailed spiny tree-rat Tuft-tailed spiny tree-rat The tuft-tailed spiny tree rat ("Lonchothrix emiliae") is a spiny rat species from South America. It is known from Brazil south of the Amazon River, where it has been found in grassland and gallery forest. It is the only species in the genus Lonchothrix. Very little is known about this rodent. It is small with an average adult weight of about 138 grams. It is nocturnal and solitary in habits. The genus and species were described by Oldfield Thomas in 1920. The genus name "Lonchothrix" derives from the two ancient greek words (), meaning "spear", and ,