Every evening, small fish and microscopic animals called zooplankton journey to the ocean surface, where they feast on microscopic plants under the moonlight before returning to the depths at dawn.
Every evening, small fish and microscopic animals called zooplankton journey to the ocean surface, where they feast on microscopic plants under the moonlight before returning to the depths at dawn. With data collected during the EXport Processes in the Ocean from Remote Sensing (EXPORTS) field campaign in 2018 to the Northeastern Pacific Ocean, scientists have now shown that some zooplankton living in the twilight zone of the ocean at depths of greater than 300 meters swim up and down also in response to shifts in light due to cloud cover.
The nightly trek from the ocean depths to the surface has been called the largest migration on Earth, because of both the number of animals who make the nightly trek and how far these tiny creatures travel roundtrip. NASA has observed this global migration with a space-based laser on the CALIPSO satellite. Scientists have also documented these migrations during events such as eclipses, full moons and storms.
"The amount that they swim is pretty remarkable given their body length, said Melissa Omand, an associate professor of oceanography at the University of Rhode Island Graduate School of Oceanography. "It's like me in Rhode Island going to Boston and back every day," she said, roughly 80 miles.
Read more at: NASA/Goddard Space Flight Center
This image, captured by an astronaut aboard the International Space Station, shows clouds casting their shadows on the Philippine Sea on June 25, 2016. (Photo Credit: ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center)
