Fact 1: Echinoderms have a unique water vascular system with tube feet.

Fact 2: Starfish and sea urchins are also echinoderms.

Given the two facts above, answer the question "what have a unique water vascular system with tube feet?" with the following options: 
- h2o
 - insects
 - sea urchins
 - bushes
 - Most plants
 - Conifers
 - orchids
 - humans


 

   sea urchins      