Photo © Woods Hole Oceanographic Institution, Deep Submergence Operations Group.Īs the ALVIN reaches the bottom of the ocean, there is no natural light. Visit the Web site for the Deep Submergence Operations Group at Woods Hole Oceanographic Institution to learn more about the ALVIN. A total dive in these tight quarters might last eight to ten hours. Three people, usually two scientists and a pilot, can barely fit. Pretty amazing, right? But how can we even see them from the ALVIN if it’s so dark down there?Ĭonditions inside the ALVIN are very cramped. Obviously, organisms who live at the deep sea vents can’t rely on the Sun instead, many of them rely on the chemicals that come out of the vents-the process they use to create food is called chemosynthesis instead of photosynthesis. And sometimes they make their own light certain species of deep sea fish and jellyfish have special light-producing cells. Animals that live in the abyssal zone feed on detritus raining down from above-or on each other. From 1,000 meters below the surface, all the way to the sea floor, no sunlight penetrates the darkness and because photosynthesis can’t take place, there are no plants, either. There is food to be had, though detritus, bits of decaying plants, and animal waste falls from above to feed the organisms in the aphotic zone.Īfter the aphotic zone, there’s complete darkness. In the aphotic zone all that’s left of sunlight is a dim, dark, blue-green light, too weak to allow photosynthesis to occur. The greatest ocean depth ever measured, at the Mariana Trench in the Western Pacific, is about 11,000 meters, almost seven miles!) Below the photic zone, from 200 to 1,000 meters, is the aphotic (a meaning without and photic meaning light) zone. (The depth of the ocean varies greatly depending on where you are here at the Juan de Fuca Ridge, the depth below me is about 2,300 meters (~1.5 miles). Two hundred meters is a lot of ocean, right? Maybe, but the depth of the photic zone is only a tiny fraction of the ocean’s total depth. Photo © University of Washington, American Museum of Natural History, and Pennsylvania State University. This upper region is called the photic zone almost all of the marine plants and tiny microscopic marine organisms that engage in photosynthesis can thrive only in the photic zone. Only the very top layers of the ocean get enough light to support plants, and most of the truly abundant animal life is crowded into the top 200 meters. At great depths, light is so scattered that there is nothing left to detect. As the light energy travels through the water, the molecules in the water scatter and absorb it.
The ocean is very, very deep light can only penetrate so far below the surface of the ocean. It’s dark down there at the bottom of the sea-darker than you can probably even imagine! Let me explain. The researchers in ALVIN certainly don’t need to wear sunglasses. It's a glorious sunny morning out at sea-I have to wear sunglasses up on deck from the glare off the water, and plenty of sunblock on my nose! In about five hours, the ALVIN will return from a day at the vents, and I can’t wait to hear about the latest data the researchers have collected.
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