Which of the Following is Characteristic of Sponges and Hydras

Question

Which of the following is characteristic of sponges and hydras?
A) lack of an actual circulatory system
B) lack of a reproductive system
C) lack of a digestive system
D) lack of a muscle system

Accepted Answer

Sponges and hydras lack an actual circulatory system. They rely on the movement of water through their bodies for the circulation of nutrients and oxygen.