Any of numerous radially symmetrical marine invertebrates of the phylum Echinodermata, which includes the starfishes, sea urchins, and sea cucumbers, having an internal calcareous skeleton and often covered with spines.

• 棘皮动物任一种属于棘皮动物门的许多呈辐射对称状的海生无脊椎动物，包括海盘车、海胆和海参，内部骨架含钙，常覆盖有棘针