All members of this phylum exhibit fivefold radial symmetry, and its name derives from the Greek for "spiny skin."
The coelom [see-lem] forms the haemal systems of members of this phylum, which is the  second largest phylum of deuterosomes. Some members of the Ophiuroidea class in this phylum have a double row of ambulacra. Organisms in this phylum contain ampullae, which form tube  feet, and a water vascular system. All members of this phylum exhibit fivefold radial symmetry, and its name derives from the Greek for "spiny skin." For 10 points, name this phylum, which includes sand dollars, sea urchins, and starfish.
The coelom [see-lem] forms the haemal systems of members of this phylum, which is the  second largest phylum of deuterosomes.
Echinodermata or Echinoderms