Fish go Deep but no Deeper
Fish are found everywhere in the world's oceans, but nowhere below a depth of 8000 meters. Dr. Paul Yancey, a professor of biology at Whitman College in Walla Walla, Washington, thinks he may now know why. Pressure at increasing depth doesn't just crush things; it can actually force water molecules into the delicate folds of the proteins that make up the body. When proteins are distorted like this, they stop working properly. Dr. Yancey has found that a molecule called TMAO can protect proteins from being distorted by water, but fish can only produce so much TMAO. Below 8000 meters, their bodies just can't tolerate the concentrations that would be required of this protective chemical. So, as a result, 8000 meters is as low as they can go.