ECHINODERMADA
Examples: Sand dollars, star fish, sea urchins, and sea cucumbers
Echinordermada normally found from the sea shore until the deep depths of the ocean in which light does not reach. This phylum has about 70,000 living species, which makes it the second largest group of deuterostomes, after the chordates. About 13,000 echinoderm species are known from the fossil record. Echinoderms are also the largest phyla that has no freshwater or earthly representatives. The echinoderms are split into five categories: Crinoidea (sea lilies and feather stars), Ophiuroidea (basket stars and brittle stars), Asteroidea (starfishes), Echinoidea (sea urchins, sand dollars, and sea biscuits), and Holothuroidea (sea cucumbers).
Echinordermada normally found from the sea shore until the deep depths of the ocean in which light does not reach. This phylum has about 70,000 living species, which makes it the second largest group of deuterostomes, after the chordates. About 13,000 echinoderm species are known from the fossil record. Echinoderms are also the largest phyla that has no freshwater or earthly representatives. The echinoderms are split into five categories: Crinoidea (sea lilies and feather stars), Ophiuroidea (basket stars and brittle stars), Asteroidea (starfishes), Echinoidea (sea urchins, sand dollars, and sea biscuits), and Holothuroidea (sea cucumbers).
CIRCULATORY SYSTEM
The circulatory system for the echinodermada is fairly simple. In echinoderms, it is composed of thickened vessel which is also know as the heart. It lacks an endothelium which is the tissue that forms a single layer of cells lining various organs and cavities of the body, especially the blood vessels, heart, and lymphatic vessels. It is formed from the embryonic mesoderm. The echinoderms is surrounded by a pericardium; a region where ultrafiltration occurs through podocytes. It has a closed circulatory system which is different from the arthropoda and an opening to the external environment called the madreporite.