Phylum Echinodermata

Upper ( ARKARUA ) Lower ( left: middle cambrian ctenocyctis carpoid fossil, right: Jurassic sea urchin )

What are Echinoderms? are a phylum of marine animals they belong to Kingdom Animalia, under Subkingdom Eumetozoa, and Superphylum Deuterostomia they are found from intertidal zone to abyssal zone of the oceans largest phylum with no freshwater or terrestrial representatives

Taxonomy *crinoids motile Eleutherozoa *Asteroidea (starfish) *Ophiuroidea (brittle stars) *Echinoidea (sea urchins and sand dollars) *Holothuroidea (sea cucumbers)  sessile Pelmatazoa *crinoids *extinct paracrinoids -> two main subdivisions of echinoderms

the echinoderms(motile eleutherozoa)

the echinoderms(sessile pelmatozoa)

Anatomy and Physiology plus Skin and Skeleton evolved from animals with bilateral symmetry the left side of the body grows at the expense of the right side, which is eventually absorbed. The left side then grows in a pentaradially symmetric fashion, in which the body is arranged in five parts around a central axis. have a mesodermal skeleton composed of calcareous plates or ossicles their epidermis consists of cells responsible for the support and maintenance of the skeleton, as well as pigment cells, mechanoreceptor cells, which detect motion on the animal's surface, and sometimes gland cells which secrete sticky fluids or even toxins. the colours are produced by a variable combination of coloured pigments, such as the dark melanin, redcarotinoids, and carotin proteins, which can be blue, green, or violet.

The Water Vascular System a network of fluid-filled canals that function in gas exchange, feeding, and secondarily in locomotion. This system is derived from both the hydrocoel and axocoel. This system may have allowed echinoderms to function without the gill slits found in other deuterostomes.

Evolution first universally accepted echinoderms appear in the Lower Cambrian period (Paul and Smith 1984). Based on their bilateral larvae, many zoologists argue that echinoderm ancestors were bilateral and that their coelom had three pairs of spaces (trimeric). Some have proposed that radial symmetry arose in a free-moving echinoderm ancestor and that sessile groups were derived several times independently from free-moving ancestors. first echinoderms were sessile, became radial as an adaptation to that existence, and then gave rise to free-moving groups.

Ecological roles of echinoderms grazing of sea urchins reduces the rate of colonization of bare rock the burrowing of sand dollars and sea cucumbers depleted the sea floor of nutrients and encouraged deeper penetration of the sea floor, increasing the depth to which oxygenation occurs and allowing a more complex ecological tiering to develop. Starfish and brittle stars prevent the growth of algal mats on coral reefs, which would obstruct the filter-feeding constituent organisms. Some sea urchins can bore into solid rock; this bioerosion can destabilise rock faces and release nutrients into the ocean. many sea cucumbers provide a habitat for parasites, including crabs, worms and snails

Habitat..

Benefits to Human….. elements of many cuisines The calcareous tests or shells of echinoderms are used as a source of lime by farmers in areas where limestone is unavailable popular collectibles

Gracias… Merci…… Domo Arigatou…. Kamsahamnida… Gracias… Merci…… Domo Arigatou…. Kamsahamnida…. Thank You… Maraming Salamat….