They rise at night. When the Sun disappears below the horizon, movement begins in the world's oceans as countless sea creatures begin their long journey upward to the surface waters.
They don't stay long. When the Sun rises, bringing light and surface predators, they again retreat into the depths of the sea, hiding in the darkness.
This endless movement – vertical migration – is believed to be the most massive migration of copepods on the planet in terms of the sheer amount of biomass involved, and it happens every day and night, and for the most part, people hardly notice it.
Scientists at the Monterey Research Institute of California are closely monitoring, analyzing thousands of hours of video footage of the phenomenon and publishing the results in a new study.
In short, migration is not a picnic. For vertical migrants who are hunted, there really is no such thing as a truly safe harbor, as predators hunt them every step of the way up and down, which usually stretches hundreds of meters in each direction.
Based on the huge number of observations recorded between 1997 and 2015 in Monterey Bay, scientists have estimated the level and type of threats they face during their daily movements.
The results are presented in Frontiers in Marine Science.
Sources: Photo: Trevor McKinnon / Unsplash
