Question

Distinguish between open and closed circulation.

Answer 1

Open blood circulation: in an open circulatory system, the blood flows freely and there are no vessels.
Close blood circulation: in this circulation blood flows inside the blood vessels.

Complete answer:
In this question we have asked the difference between open and closed circulation. So, here are some differences between open and close circulation.

Sl. No.	Open circulation	Close circulation
1.	The hemolymph flows freely and there are no vessels.	The blood circulates within the vessels.
2.	We can’t distinguish between blood and interstitial fluid.	Blood is present inside the vessels and interstitial fluid is present outside the vessels.
3.	It is present in arthropoda and mollusca.	It is present in vertebrates and annelids.
4.	Blood flow is slow.	Rapid blood flow.
5.	They can’t control the volume of blood.	They can control the volume of blood by relaxation and contraction.
6.	Open spaces are present- sinuses and lacunae.	Close vessels are present- arteries and veins
7.	Blood is pumped directly to the organs.	Blood is pumped via arteries and veins.
8.	Capillary system is absent.	Capillaries are present.
9.	Respiratory pigments are absent.	Respiratory pigments like hemoglobin are present.
10.	It doesn't transport gases.	Transport gases.
11.	Blood pressure is low hence, this system is less active.	Blood pressure is high hence, this system is more active
12.	Supply and elimination of materials are very slow.	Supply and elimination of materials are very rapid.
13.	Blood takes more time to complete one round.	Blood takes less time to complete one cycle.

Note: You can add more differences to this table as there are a lot more differences between open and closed circulation.
Humans have a closed circulatory system. The blood is circulated in the close vessels and pumped by the heart. The blood travels through arteries and veins and transports important molecules.