It's no wonder that the bottom of the Arctic Ocean is considered to be one of Earth's last frontiers. Much of the year it is located under thick ice in a remote location, making it difficult and expensive for research teams to plan expeditions. Even without these logistical challenges, the depth and darkness of the frigid water make exploration even more daunting. But with the use of an icebreaker, a team of researchers from the Woods Hole Oceanographic Institution set out in 2007 to explore the Gakkel Ridge, part of the mid-ocean ridge system that runs almost directly below the North Pole. They used cutting-edge submersible vehicles to document in pictures and video the geology and biology of this undersea feature for the very first time.

At Earth's mid-ocean ridges, hot rock from Earth's core is forced up to the seafloor's surface and new ocean floor forms in a process known as seafloor spreading. It's here, too, that the emerging molten rock produces formations called vents, or chimneys. Scientists study these features to better understand geological processes, in particular aspects of plate tectonics. But they also seek to learn more about deep-sea communities that live around these vents.

The Gakkel Ridge has been geologically isolated from other mid-ocean ridges for more than 20 million years. This isolation has long intrigued scientists. Team researchers learned from a 2001 expedition that Gakkel Ridge rocks are made of mantle rock, which is different than the basalt rock found at other known mid-ocean ridges in the world. Scientists suspect that the chemical reactions between the Gakkel Ridge rocks and seawater may produce a different mix of chemicals—one that would in turn support the unique forms of life discovered there. In fact, because the Gakkel Ridge rocks were thought to be similar in composition to rocks that emerged billions of years ago, early on in Earth's history, researchers suspect life at these Arctic vents may provide clues to the earliest life on our planet.

What's been discovered at deep-sea ridges like the Gakkel Ridge offers a clear lesson in how geology drives biology; that is, that the physical conditions dictate the kinds of life that evolve. Through a process called chemosynthesis, bacteria use energy stored in the mix of chemicals around them to grow and multiply. These bacteria, then, are equivalent to land plants, which derive energy from sunlight and serve as the base of the terrestrial food web. In the absence of sunlight, deep-sea bacteria derive the energy to support life from reactions between oxygen and abundant chemical compounds such as hydrogen sulfide and ammonia. Larger, more complex organisms either live on the bacteria that grow in their bodies or they feed on each other. As is confirmed by the still images and video footage in this interactive activity, a variety of vent life has evolved to take advantage of this strategy.

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