To conduct the research, Cohen travelled to the Svalbard archipelago in the Arctic Ocean - northeast of Greenland, if you're searching a globe - conducting research both on a research vessel out at sea and at a light observatory on land. One of those biological impacts is on the visual sensitivity rhythms of krill. There is also more light than you would think, even when the sun is below the horizon, and it has biological impacts.' Instead, you've got organisms that are active throughout that polar night period when the sun is below the horizon. 'Our work has found that is not the case. 'The dogma for a long time was that when the sun stays below the horizon, biology just goes into suspended animation, and then everything kicks back up again when the sun comes back above the horizon in the spring,' said Cohen. Jonathan Cohen, associate professor at the University of Delaware's School of Marine Science and Policy in the College of Earth, Ocean and Environment, served as the lead author on the paper and said that it ties into larger work looking at the biological processes that take place during Arctic polar night.

When it is darkest in the Arctic polar night, that's when they swim to the surface in search of bioluminescent food.ДЄ new study published in PLOS Biology looked at this visual sensitivity rhythm in Arctic krill during the Arctic polar night. When it is lightest in the Arctic polar night - a time of year at high latitudes when the sun remains below the horizon for the entire 24-hour period - usually around the middle of the day known as midday twilight, the Arctic krill know to swim down to the bottom in order to hide from predators. It turns out that the same thing happens for Arctic krill.

During the night time, our eyes become more sensitive to adjust to the lack of light available. Because of this, our visual system changes so that it can be ready to work under brighter light conditions. During the day, it is typically lighter than at night.

What is night changes about