The arthropod blood vascular system is termed an open system because
A) blood is not always enclosed in vessels.
B) there is no heart to pump the blood.
C) it does not have a haemocoel.
D) it originated from the coelom which is open.
E) All of the answers are correct.

Question

Quizplus · Accepted Answer

In an open circulatory system, like that of arthropods, the blood (or hemolymph) is not always confined within vessels but may fill body cavities, allowing direct contact with tissues.

The Arthropod Blood Vascular System Is Termed an Open System