The Jellyfish of Copenhagen

Unlike French toast, Danish pastry is actually a specialty of the country it is named for. So while visiting friends in Copenhagen, we had little choice but to make frequent visits to the "Lagkagehuset," pronounced "La-Kay-Who-set" and meaning "The Layer Cake House." Our friend Nisha assured us that this was the best bakery in Copenhagen, and judging by their pastry this seems likely. (Broader sampling may be necessary at some point.) Lagkagehuset is next to one of the many canals that crisscross Copenhagen, and one morning as we sat eating our pastry, I noticed something floating by, maybe a plastic bag. The way it moved caught my eye because it didn't seem entirely passive. I went to take a closer look, but it was gone, moving quickly downward in the water. Too quickly to be a plastic bag, unless there was a sudden and sharp down current. Watching for a moment more, another floated into view, and it was a jellyfish! A big one, as big around as a dinner plate, but with tentacles only a hand long. As we stood and watched dozens more gradually floated by, apparently feeding on the numerous small silver fish moving in schools through the canals. I was surprised to find so much active, apparently healthy sea life in the middle of a major metropolis. Over the next few days every time I glanced into the canals there were jellyfish. Copenhagen's water seems to support lots of little fish, and the jellyfish seem to be their main predators. I've heard that in at least some cases (e.g. where the Mississippi's nutrients spill into the Gulf of Mexico) jellyfish thrive in polluted waters. The water in the canals of Copenhagen look pretty clear, but it is a major metropolis, so I'm not sure if the jellyfish in this case indicate dirty water or a healthy ecosystem. Either way, it is cool to see them floating by.