Fact 1: Echinoderms lack respiratory and excretory systems.

Fact 2: Echinoderms in the diorama include the crinoids and blastoids.

Given the two facts above, answer the question "What lack respiratory and excretory systems?" with the following options: 
- They may not survive.
 - members of their own species
 - platypus
 - humans
 - crinoids and blastoids
 - passenger pigeons
 - graptolites
 - whales


 

     crinoids and blastoids    