life on Earth is dependent upon photosynthesis, the process by which plants
make energy from sunlight. However, at hydrothermal vents in the deep
ocean a unique ecosystem has evolved in the absence of sunlight, and its
source of energy is completely different: chemosynthesis. Chemosynthesis
is the process by which certain microbes create energy by mediating chemical
reactions. So the animals that live around hydrothermal vents make their
living from the chemicals coming out of the seafloor in the vent fluids!
Because they are a local food source, hydrothermal vents typically have
high biomass, in stark contrast to the very sparse distribution of animals
outside of vent areas where animals are dependent on food dropping down
microbes provide the foundation for biological colonization of vents.
Chemosynthetic microbes live on or below the seafloor, and even within
the bodies of other vent animals as symbionts. Where microbial mat covers
the seafloor around vents, grazers such as snails, limpets, and scaleworms
eat the mat, and predators come to eat the grazers. Tubeworms flourish
in small clumps, waving in the warm fluids. A typical picture of an active
hydrothermal vent is therefore one with shimmering warm hydrothermal fluids,
tubeworms and many other vent species, all densely clustered around the
vent, with white microbial mat material covering the surrounding area.