Explain in short the mechanism of circulation in living organisms.

(N/A) All living cells require a constant supply of nutrients,$O_{2}$,and other essential substances to survive. Simultaneously,metabolic waste products must be removed from these cells.
To facilitate this,organisms have evolved various transport mechanisms:
$(i)$ Simple organisms like sponges and coelenterates circulate water from their surroundings through their body cavities,allowing cells to exchange substances directly with the water.
$(ii)$ More complex organisms utilize specialized body fluids to transport materials efficiently throughout the body.
$(iii)$ In higher organisms,including humans,blood and lymph serve as the primary body fluids for the transport of nutrients,gases,and waste products.