Question

Open vascular system is found in:

• A. fish
• B. man
• C. prawn
• D. snake

Answer 1

The correct option is C

prawn

Open circulatory systems evolved in crustaceans, insects, mollusks and other invertebrates. Here, a heart pumps the blood fluid into a hemocoel. They are called open circulatory system because blood is not contained in the closed circuit of vessels. So, blood flows in open-ended vessels and once it reaches the end of the vessels, the blood flows directly over the tissues. So, the tissues are always covered with blood. The hemocoel moves back to the vessels through intake valves or pores known as ostia.