A cardiovascular system is not necessary in the hydra because the hydra
A) is an aquatic animal.
B) has no skeleton.
C) is only two cells thick.
D) has tentacles to move water.
E) does not move rapidly.

Question

Quizplus · Accepted Answer

The hydra is only two cells thick and relies on simple diffusion to transport materials throughout its body. This means that a cardiovascular system is not necessary as nutrients and gases can easily pass through the thin layer of cells.

A Cardiovascular System Is Not Necessary in the Hydra Because