The biggest migration happens ...

Two views of a paralarval wunderpus octopus taken in Anilao, the Philippines. The body is about the size of a thumbnail. The spots are developing chromatophores that help the octopus blend into its environment. Credit: Linda Ianniello

The biggest migration in the world happens ... every night.

“Blackwater” divers photograph the largest migration of animals on the planet

Every night at sundown, a great mass of mostly small sea creatures rises up from the depths into the topmost layers of the planet’s oceans. This daily vertical migration is the largest on Earth—an estimated 11 billion tons of animal biomass travels miles upward each night and then, before the sun rises, returns back to the dimly lit “twilight zone” below. The animals make this journey to feed on the organic material closer to the water’s surface and do so at night to avoid being eaten by the larger predators swimming there.

The nighttime migration was first discovered in the 1940s by the U.S. Navy, whose new sonar technology began pinging congregations of objects in the water column. Since then researchers, hobby divers and photographers have gone out to scuba dive at night and observe these nocturnal creatures.

Artistry at the highest level, spoken here.

Blackwater diving is done at night to a maximum depth of 60 feet, and divers are tethered to their boat by a rope. A light attached to a diver’s underwater camera illuminates the dark water in small patches, helping that person spot tiny animals (some no bigger than a pea), which are often mostly transparent and fast-moving.

Credit: Linda Ianniello

Larval thimble jellyfish in Florida: Larvae that get under people’s bathing suit sting their skin and cause “seabather’s eruption,” an itchy rash. Ianniello says she’s seen fewer of these creatures in the past five years, but the cause remains unknown.

Read the entire SA piece as the images taken, in the name of science, will totally astound you. :)