On this post-Thanksgiving day of rest, digestion, and reflection on the ability of food to bring families and friends together, I thought it would be appropriate to share some information I learned this past week about food and its ability to bring other, more disparate groups together. The largest migration on planet Earth is not, as I would have guessed, a seasonal migration. It is a daily migration of numerous species of marine organisms, from tiny zooplankton to the largest marine predators. Across the world, entire marine ecosystems migrate from the ocean surface at dawn to anywhere from hundreds to thousands of meters depth. They then return back to the surface at dusk. The motivation for this massive migration? Well, that depends on where you are in the food chain. Smaller organisms migrate to the dark depths of the ocean to avoid predation, while larger organisms generally follow in hopes of catching a meal.
The hunt for food mobilizes entire ecosystems on a daily basis! But why does this migration make any sense if the little creatures driving it are constantly being pursued? Turns out that smaller animals require less oxygen than larger ones, and so the depth of migration depends on where in the ocean oxygen limitation begins to occur. Small animals hoping to avoid becoming someone’s next meal migrate just far enough into this zone that larger predators cannot follow.
Just a lil’ piece of science to put everyone’s turkey day in perspective. Happy Thanksgiving to all!