Give a scientific reason: The blood vascular system of leeches is also called the haemocoelomic system.

(N/A) $\rightarrow$ In leeches,a true blood vascular system is absent. Instead,the coelomic space and its fluid have been modified to form the circulatory system. Hence,it is called the haemocoelomic system,and the coelomic fluid is referred to as haemocoelomic fluid.
Blood appears red due to the presence of the respiratory pigment haemoglobin or erythrocruorin,which is found dissolved in the plasma.
Free amoeboid blood corpuscles are present,but there are no red blood corpuscles (erythrocytes).