So in Ichtyology class I was learning about the Gas Gland. It's an organ fish use to keep themselves buoyant in water. One type of gas gland extracts Oxygen from capillarries to inflate the gland, and then releases it back into the blood supply to lower it's body in the water. I was thinking that the gas gland was probably what had evolved into the lung and asked my proffessor if that's where it evolved from. He didn't seem to know but thought that it seems like the only thing that the lung probably did evolve from. So what does everybody think about that? I thought it was pretty cool for an organ to go from controling buoyancy, to allow life to go even higher and emerge from the water and have a whole new world open up to it.