One #Hakai video I just posted on was on Diel Vertical Migration of #zooplankton (also motile #phytoplankton). DVM is the largest movement on biomass on the planet, occurring every morning and evening in #lakes and #oceans, as much as 100s of meters (impressive for something a couple mm long). They swim up to feed on algae at night and to avoid visual predators. They also save on energy because deeper cooler water means slower metabolism.
https://youtu.be/OSCZ6athDGI?list=PLD5wTqJwsmGxI9G2B8rM7zV7TIG-mJ_c8