How do sponges exchange O₂ and CO₂?

Step-by-step solution

Mechanisms of breathing vary among different groups of animals depending mainly on their habitats and levels of organisation. Lower invertebrates like sponges, coelenterates, flatworms, etc., exchange O2 with CO2 by simple diffusion over their entire body surface . Earthworms use their moist cuticle and insects have a network of tubes (tracheal tubes) to transport atmospheric air within the body. Special vascularized structures called gills (branchial respiration) are used by most of the aquatic arthropods and moll