How do underwater volcanoes affect marine life?

Just like humans, who gravitate toward mild climates, many marine organisms live in warmer areas of the oceans. The sun heats the surface of the ocean more than lower layers, so that's where most sea creatures live.

Deeper waters are much cooler. As you go lower, the water usually gets colder and colder until around 100 meters down, where it reaches about 39 F. This boundary is known as the thermocline. Below it, the temperature remains fairly constant. Few organisms can survive at such cold temperatures.

Image above: A view of a hydrothermal vent (top photo). The super-heated black water pouring from the vent provides high-energy chemicals that sustain the tubeworms (bottom photo) and other organisms that thrive in this unlikely habitat. Credit: Woods Hole Oceanographic Institution

An exception to deep waters being cold are areas just above hydrothermal vents. These are fountains on the ocean floor that spout water as warm as 400 degrees Celsius (750 F). They form when seawater seeps into the Earth's crust and mixes with magma or lava from an underwater volcano.

Hydrothermal vents are sometimes called "black smokers." That's because the erupting hot water is rich in minerals, causing it to look like black smoke.

Scientists used to believe that all life depended on energy from the sun. But that was before the first hydrothermal vent was discovered in 1977.

Since then, more than 300 species of clams, crabs, tubeworms and other creatures have been found near these vents. The deep-sea organisms get their energy from chemicals and nutrients in the hot, hydrothermal water, rather than from the sun.

Through the use of remotely operated submarines and other equipment, more information is always being gathered about hydrothermal vents and their surrounding environments. In fact, some NASA researchers now believe that life on Earth may have begun deep down in the ocean near these vents.

This week's question comes from Mr. Dolphin's ninth-grade class at Endicott High School in Endicott, New York. The answer was written by University of Miami sophomore Thomas Murphy, as part of a science
writing class developed through the NASA-sponsored Earth System Science Education for the 21st Century (ESSE-21) program, and edited by Dan Stillman, Institute for Global Environmental Strategies.