Karen LaFleur, Currents: Vertical Migration

Around 5 billion metric tons of krill, jellyfish, plankton, and other deep-sea creatures migrate each night from ocean depths to the surface. They make the journey to feed and sometimes mate before sinking back into the dark depths. This is the largest bio-mass migration on the planet. Their movement is important to the ocean’s food chain. As creatures swim up-and-down their passage causes turbulence and moves essential nutrients across water-layer boundaries.

---