Difference between Open and Closed Circulatory System

Almost all multicellular organisms need a circulatory system to transport oxygen and nutrients through the body. Evolution has led to the existence of two types of circulatory systems, namely:

  • Open circulatory system: It is primarily found in invertebrates. Here, the blood flows freely through cavities since there are no vessels to conduct the blood.
  • Closed circulatory system: It is found in vertebrates and a few invertebrates, like earthworms. This system has vessels that conduct blood throughout the body.
Difference Between Open and Closed Circulatory System

Open and Closed Circulatory System

The main difference between the open and closed circulatory systems is the way blood flows in an organism. Blood can flow through vessels inside the body, such as arteries and veins. This type of circulation is called closed circulation. Open circulation happens when there are no vessels to contain the blood, and it flows freely through the cavities of the body.

Also Read: Human Circulatory System

Difference between Open and Closed Circulatory System

Vertebrates and a few invertebrates have closed circulatory systems. The open circulatory system, on the other hand, is most commonly seen in invertebrates such as cockroaches and crabs.

The other major differences between open and closed circulatory system are summarised below:

Open Circulatory System Closed Circulatory System
The hemolymph directly bathes the organs and tissues. The blood circulates within closed vessels.
The blood and interstitial fluid cannot be distinguished. Blood and interstitial fluid are distinct.
Present in molluscs and arthropods. Present in annelids
and vertebrates.
Blood is pumped into the body cavity. Blood is pumped through the vessels by the heart.
Dorsal blood vessel present. Dorsal and ventral blood vessels present.
Capillary system is absent. Capillary system is present.
Blood is in direct contact with the surrounding tissues. Blood is not in direct contact with the tissues.
Nutrients are exchanged directly between blood and tissues. The nutrients are exchanged via tissue fluid.
No transport of gases. Gases are transported.
The fluid flowing in this system is called hemolymph. Fluid flowing in this system is called blood.
No respiratory pigments are present. Respiratory pigments are present.
The volume of blood cannot be controlled. The volume of blood can be controlled by the contraction and relaxation of blood vessels.
Blood flow is slow. Blood flow is rapid.
The open spaces are called sinuses and lacunae. Closed spaces involve arteries and veins.
Organisms with OCS: Snails, clams, cockroaches and spiders. Organisms with CCS: Humans, squids, cats, earthworms.

Also Read: Circulatory System

To learn more about the difference between closed and open circulatory systems, keep visiting BYJU’S website or download the BYJU’S app for further reference.

Related Links:

Human Circulatory System – Transportation
Double Circulation

Frequently Asked Questions


What is open and closed circulation?

In open circulation, the blood is not enclosed in the blood vessels and is pumped into a cavity called hemocoel. On the contrary, in closed circulation, the blood is pumped through the vessels separate from the interstitial fluid of the body.


What type of circulatory system do humans have?

Humans have a closed circulatory system. The blood is enclosed in the vessels and the heart while circulating. The blood travels through arteries and veins and carries important molecules throughout the body.


What is the advantage of a closed circulatory system over an open system?

In a closed circulatory system, blood is transferred faster than in an open circulatory system. That is why the closed circulatory system is more advantageous than the open system.


What are the main components of a (closed) circulatory system?

The main components of a (closed) circulatory system include:

  • Heart
  • Blood
  • Blood vessels

Which organism has an open circulatory system?

Insects have an open circulatory system. Unlike humans, the blood in insects flows freely throughout the body.

Also Read: Earthworms

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