Echinoderms have a unique water vascular system with tube feet.
Starfish and sea urchins are also echinoderms.
Sea urchins have a unique water vascular system with tube feet.
what have a unique water vascular system with tube feet?
Options:
[1] h2o
[2] insects
[3] sea urchins
[4] bushes
[5] Most plants
[6] Conifers
[7] orchids
[8] humans