By mechanisms still unknown

There should be a word for information that is learned a second time, after being acquired and subsequently forgotten. For example, I'm fairly sure at one point I learned that unlike in human anatomy, whales' alimentary canals don't connect to their respiratory systems. I probably picked it up from a textbook, filed it away as important for testing purposes, and promptly expunged it in favor of some dumb song lyrics. 

When I learned it again, it was a miniature revelation. Imagine how weird we would seem to whales, if whales ever studied our anatomy. We use the same forward manifold for air intake as we do for the ingestion of liquids and solid nutrition. To make matters worse, we can't stop breathing for extended periods when we eat and drink, meaning that the two actions must be controlled simultaneously. It's disgusting when you consider it (from the whales' perspective). They have discrete, unentangled means of feeding and respiration, with no potential cross-routing. (This also means that if you're a cartoon fish who's swallowed by a whale, you will not be exiting via the blowhole, unless you begin aggressively tunneling through flesh into the lungs.)

Our mouths are essentially reverse cloacas, multipurpose ports commingling biological processes that are mutually exclusive, even hostile to each other's purpose. Trust me, as an emergency services provider, when excessive amounts of air or liquids/solids take the wrong route into the thorax, the results are unhealthy. 

Anyway, I'm researching whales for a story in which someone is trying to talk to them... sort of. Here's a video about how they sing, or at least how we think they do it. We're not quite sure.