Zooplankton are animals that drift with the ocean currents. Tiny zooplankton are harvested from the San Francisco bay using a plankton net, and then placed in a tank of filtered bay water.
Like moths, they are attracted to lights, particularly in the blue spectrum. No one has really studied their behavior so scientists do not know why zooplankton do this. But the effect is very strong, and since zooplankton are made up of many different species of animals, this would be an important question to understand.