Why are highly branched gills more efficient then gills that are not branched?

Highly branched gills are more efficient because their increased surface area allows for greater gas exchange between water and blood. The branching structures create more sites for oxygen to diffuse into the bloodstream while carbon dioxide is expelled. This design enhances the gills' ability to extract oxygen from the water, making it particularly advantageous in environments where oxygen levels may be low. Additionally, the increased surface area helps to maximize the overall efficiency of respiration in aquatic organisms.