You are presented with the quiz "What is an example of an animal that lacks a respiratory and excretory system?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "echinoderms lack respiratory and excretory systems" and "starfish and sea urchins are also echinoderms". 

So, what's the best answer to the question?


 

     Starfish      