The Earth-Shaping Animal Migration No One Ever Sees A closer look at one of nature’s hidden wonders. This dance between light and dark, warm and cold, and predator and prey is called diel vertical migration (pronounced dial). “If you can think of an open ocean animal, there’s a pretty good chance that it goes through some form of vertical migration,” says Rebecca Helm, a marine biologist at the University of North Carolina Asheville. All day long, the sun’s rays charge up teeny, tiny algae called phytoplankton in the ocean’s uppermost layer. When all those tiny phytoplankton undergo photosynthesis at the surface, they consume carbon dioxide, says Helm.