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14 of the greatest animal migrations

By: Bryan Nelson on Sept. 27, 2010, 9 a.m.

Photo: cursedthing/Flickr

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Zooplankton are the countless numbers of organisms that float in the water column of the world's oceans and seas and includes organisms as diverse as jellyfish, krill and juvenile fish.

Their migration is different because it moves up and down through the ocean's depths rather than traversing a landscape (although they can do this, too!). Known as vertical migration, the movement of zooplankton rivals the seasonal migration of more famous migratory species such as caribou or Arctic tern.

Despite their tiny size, some zooplankton swarms swim a vertical distance of 3,000 feet nearly every day in the continual search for food.