How many of you guys have seen this fish, never knowing that instead of a swim bladder that they have lungs?
These fish belong to the only genus of vertebrates that have lungs, but no trachea. I find it fascinating that this heavily implies that the evolution of lungs was initially independent of the evolution of trachea rather than those body parts developing together at the same time.
They regularly breathe air to increase their oxygen supply, regardless of water levels or quality. From what I can find on them, the only thing stopping them from being able to be entirely terrestrial is the fact that they need their bodies to stay moist.
I find it funny that people constantly demand fossil intermediates for various traits when there are living proofs of concept.