NBN file photo.

When I toured Northwestern’s campus before I applied here, the one feature of the campus that drew me was the Lakefill. When I stepped out onto that little park we had built for ourselves, looking out on the amazing view of the Chicago skyline, my immediate thought was, “I HAVE to come here.” And as I spent many days and nights wandering around, iPod blaring, pretending to be brainstorming yet really procrastinating, I spent a good amount of time staring into the lagoon we designed into it, watching the koi swim by. But as the Chicago winter approaches I can’t help but wonder: What happens to those fish when the lagoon freezes in the winter? Are they encased in the ice, waiting to be thawed out and reanimated come springtime, like some caveman in a low-grade science fiction movie?

Not really. As anyone who has so much looked at a glass of ice water knows, ice floats, because of a peculiar property of water that makes it expand as it get colder at temperatures below about 40 degrees. So when temperatures plunge below freezing, a sheet of ice floats to the top, which then acts as an insulating layer, keeping the water below at a (relatively) stable temperature. The fish move toward the bottom, where the water stays at about 39 degrees Fahrenheit. This is what makes ice fishing possible (although not necessarily sane). But because they’re cold-blooded, and not as much sunlight can poke through the ice to warm them, the fish will slow down a bit, in many cases entering a state of hibernation, shutting down metabolic functions temporarily. But just like any hibernating animal, as the temperature rises the fish return to their lives as normal, being gawked at by nerdy Northwestern students.

Bonus fun fact: Although koi are sometimes called “Japanese goldfish,” they’re not really goldfish. Although both evolved from types of carp, koi are a specific breed of the common carp, while goldfish are a distinct species evolved from Crucian carp, which lack the little mustache-like apparatuses that koi and common carp have. In the late 18^th and early 19^th centuries, farmers in Japan who had been raising carp to supplement their diets noticed that some had mutated, taking on white, red and orange color patterns. They used selective breeding to separate out the colors, creating the bright, distinct patterns we see today.

Think I won’t get any more random than this? Try me. Send questions to ubernerdnbn@gmail.com.