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
Spiny orb-weaver the smaller male lacks the spiny projections and instead has four to five stubby dark projections. Orb-weavers' bites are generally harmless to humans. , the World Spider Catalog accepted the following species: Spiny orb-weaver Spiny orb-weavers is a common name for Gasteracantha, a genus of spiders. They are also commonly called spiny-backed orb-weavers, due to the prominent spines on their abdomen (compare genus "Isoxya"). These spiders can reach sizes of up to in diameter (measured from spike to spike). Although their abdomen is shaped like a crab shell with spikes, it is not to be confused with a crab spider.