Question

Do insects have blood?

Answer 1

Hint: The insects are invertebrates which have an open circulatory system. They do not possess any blood vessels. The insects do not require any oxygen transport system.

Complete answer:
Insects are organisms that do not possess any blood vessels. The circulatory system is the open type which means the tissues are soaked in the fluid which is analogous to the blood. This fluid is known as haemolymph. This haemolymph flows freely inside the body cavity.

Haemolymph does not contain haemoglobin which is the oxygen-carrying molecule. Hence it is not red in colour. The oxygen required is obtained through spiracles. The hemolymph carries nutrients and transports them to all the tissues. The hemolymph is made up of plasma which is the fluid part and the hemocytes which are the cells suspended in the plasma. The primary oxygen transporter in the hemolymph is the hemocyanin which is a copper-containing pigment. It is also made up of water, salts like sodium chloride, certain proteins and amino acids, carbohydrates etc.

The hemocytes are found free-floating and function as the cells of the immune system. The hemolymph also contains certain nucleating agents which protect against extracellular freezing.

Thus, we can say that the insects have a fluid called hemolymph which is analogous to the blood.

Note: The insects have an open circulatory system as they do not require any system for the transport of oxygen as compared to a closed circulatory system where the demand for quick transport of oxygen is high. The insects which live in oxygen-deficient places have hemocyanin for the transport of oxygen.