Further discussion of life around these vents can be
found at:
http://seawifs.gsfc.nasa.gov/OCEAN_PLANET/HTML/ps_vents.html
The discussion of what attracts the animals is given by
a quote from the site:
"Water pouring out of vents can reach temperatures up to
about 400 C; the high pressure keeps the water from boiling.
However, the intense heat is limited to a small area. Within
less than an inch of the vent opening, the water temperature
drops to 2 C, the ambient temperature of deep seawater.
Most of the creatures that congregate around vents live at
temperatures just above freezing. Thus chemicals are the
key to vent life, not heat. "
