Why do multicellular organisms require specialised gas exchange surfaces?

Multicellular organisms require specialised gas exchange surfaces for a number of reasons:

• Simple diffusion is insufficient to meet the demands of the organism. The processes the organism must carry out require more amount of energy therefore require more oxygen must enter their bodies. This amount cannot be achieved by simple diffusion.
• The rate of diffusion is too slow in multicellular organisms to meet the needs of the organism.
• They have a small surface area to volume ratio (SA:V) 
• The organisms are more…