Why Does Deep Sea Life Look So Strange?

Scientists have found that the darkest and deepest parts of our oceans are teeming with life. But how exactly do they survive down there?

At its deepest, the ocean floor may as well be another planet.

Evidence for this is being provided by the National Oceanic and Atmospheric Administration (NOAA) ship Okeanos, currently floating over the deepest part of the Pacific Ocean and dropping robot cameras to the ocean floor. Okeanos' mission: to study the geology and deep-sea ecosystems in and around the 1,500-mile long Mariana Trench, which at its lowest point is deeper than Mount Everest is tall.

Actually, right now the Okeanos is parked in the port of Saipan for a well-needed breather, but will resume its 24/7 mapping cruise on May 20. After that, you can check out a live video feed from the Okeanos' submersible robots for a chance to see deep sea creatures that no human has ever even glimpsed before.

And these are seriously weird creatures: Deep sea life includes specimens like viperfish, gulper eels, giant isopods and excellently-named fishies like the hydromedusa jellyfish.

In today's DNews dispatch, Julian Huguet investigates the reasons why life at the bottom of the sea is so radically different than life on terra firma.

The fast answer is also the most accurate: It's all about environment. Like any animal, deep sea creatures have evolved according to their habitat and environment. When you've got several kilometers of water overhead, the principal environmental factor is pressure.

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For every kilometer below the surface of the ocean, pressure becomes 100 times greater than what we experience on land. At the ocean floor, creatures are living in an environment wholly different than anywhere else on the planet.

This results in animals with startling body adaptations. Deep-sea creatures have soft and watery body compositions that keep them from compressing. The pressure even affects these animals on a cellular level. Their cell membranes need unsaturated fats to keep them liquid -- anything solid gets crushed and frozen.

As such, jellyfish, sponges and eels can survive at severe depths, but they have other problems to deal with. Since no light penetrates to the depths they swim, deep sea creatures can't depend on plant life for food. They must eat one another or feed on dead organic matter falling from above. In some cases, fish and shrimp feed off chemicals oozing from geologic fissures.

Sex is an issue, too. The task of finding a mate in the sparsely populated darkness has resulted in extreme adaptive solutions, like hermaphroditic fish that can reproduce with pretty much anyone they bump into.

Check out the DNews video for some frankly alarming images and keep an eye on NOAA's Okeanos Explorer page for further discoveries.

-- Glenn McDonald Read More:

LA Times: Watch NOAA's Live Feed of a Hidden, Watery World

Live Science: 'Supergiant' Crustaceans Found in Deep Sea

BBC: What Does it Take to Live at the Bottom of the Ocean?