Marine biologists patrol an undersea world that resembles a rocky landscape more than
it does an ocean floor. The scientists cruise through the water in a remote-controlled
submarine in complete darkness. If they shine a light, what they see is something totally
unexpected: tall rock formations jutting up from the ocean floor and surrounded by black
smoke, similar to underwater chimneys. Circling these rocky peaks are worm-like
organisms. They resemble red-and-white tubes-ke giant peppermint sticks. What is
even more amazing is that these odd creatures are not only alive, but living in this dark
underworld away from light and the sun's energy. So how is that possible? Underwater
vents somehow create an environment where these striped creatures can exist. Ever
since the discovery of the creatures in 1977, scientists have been both baffled and
intrigued by the very existence of these strange creatures that grow out of vents on the
ocean floor away from sunlight. What scientists have leamed is that there are large
cracks, or vents, in the ocean floor where these creatures exist. These deep-sea vents
can be compared to the kinds of geysers you see on land. But, instead of shooting up
from the ground, they shoot up from the bottom of the ocean floor. According to the
National Oceanographic and Atmospheric Administration (NOAA), the billowing black
smoke that exists on the ocean floor is probably the result of hot liquids bursting from
the vents and miding with the extremely cold ocean water. What is so shocking about
this information? Well, scientists always believed that life on Earth could not exist
without sunlight. Yet somehow energy is being released below the surface of the water,
and all without the benefit of the sun. It's as if these undersea vents have created a
unique ecosystem, deriving energy from Earth itself. Scientists even have named the
underwater creatures. They are called extremophiles-a fancy name for organisms that
live in an extreme environment in the ocean vents. Scientists continue to study
extremophiles to determine just how the creatures tum these vents into sources of
usable energy

Using the RACES strategy, identify the central idea of the passage. Use evidence from
the text to support your answer.