From MarineSpecies Introduced Traits Wiki
phylum of marine coelomate animals that are bilaterally symmetrical as larvae but show five-rayed symmetry as adults and have a calcareous endoskeleton and a water vascular system. It includes the classes Crinoidea (sea lilies and feather stars), Asteroidea (starfish), Ophiuroidea (brittle stars), Echinoidea (sea urchins) and Holothuroidea (sea cucumbers).
- Lawrence, E. (2005). Henderson’s dictionary of biology. Pearson Education Limited, 13th ed., Harlow. 748 p.