Zooplankton Are Responsible for the Largest Migration on Earth.

Zooplankton (a group of ocean-dwellers made up of microscopic animals living in the ocean, the young of certain species, and some jellyfish) generally drift around in deeper waters during the daylight to avoid predators. Then at night, they venture up to the surface to feed on the phytoplankton that live there. This daily journey is considered the largest migration on Earth. In fact, so many creatures make this journey that satellites can pick up their movements from space!