I still can't fucking get over how cetaceans adapted to spend their entire lives in the water and just never bothered to redevelop water-breathing. there's motherfuckers who spend an hour or more diving and the evolutionary solution is just "breathe a lot on the surface and then lower your heart rate to a near-hibernation level while actively cruising the seafloor for stuff to eat". totally insane solution to one of the oldest solved problems in biology





















