List of species that form a part of the echinoderm fauna of South Africa
Map of the Southern African coastline showing some of the landmarks referred to in species range statements
The list of echinoderms of South Africa is a list of species that form a part of the echinoderm (Phylum Echinodermata) fauna of South Africa, and includes the starfish, feather stars, brittle stars, sea urchins and sea cucumbers. The list follows the SANBI listing on iNaturalist.
An echinoderm (/ɪˈkaɪnəˌdɜːrm,ˈɛkə-/) is any member of the phylumEchinodermata (/ɪˌkaɪnoʊˈdɜːrmətə/; from Ancient Greekἐχῖνος (ekhînos) 'hedgehog', and δέρμα (dérma) 'skin') of marine animals. The adults are recognizable by their (usually five-point) radial symmetry, and include starfish, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Adult echinoderms are found on the sea bed 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 the largest phylum that has no freshwater or terrestrial members.
Aside from the hard-to-classify Arkarua (a Precambrian animal with echinoderm-like pentamerous radial symmetry), the first definitive members of the phylum appeared near the start of the Cambrian. One group of Cambrian echinoderms, the cinctans (Homalozoa), which are close to the base of the echinoderm origin, has been found to possess external gills used for filter feeding, similar to those possessed by chordates and hemichordates.
The echinoderms are important both ecologically and geologically. Ecologically, there are few other groupings so abundant in the biotic desert of the deep sea, as well as shallower oceans. Most echinoderms are able to reproduce asexually and regenerate tissue, organs, and limbs; in some cases, they can undergo complete regeneration from a single limb. Geologically, the value of echinoderms is in their ossifiedskeletons, which are major contributors to many limestone formations, and can provide valuable clues as to the geological environment. They were the most used species in regenerative research in the 19th and 20th centuries. Further, some scientists hold that the radiation of echinoderms was responsible for the Mesozoic Marine Revolution. (Full article...)
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