Challenger Deep
Unusual life forms may have evolved under conditions of extreme pressure in
this 11,000-meter-deep trench, the deepest part of the world’s oceans.
New Zealand
This region has a full spectrum of habitats supporting seafloor life (hydrothermal
vents, cold seeps, whale carcasses, and wood from shipwrecks and trees) in close
proximity. How have species evolved in these diverse settings?
Deep Atlantic vent communities (2500-3650-meter depths) are
dominated by swarms of shrimp called Rimicaris exoculata.
Shallow Atlantic vents (800-1700-meter depths) support dense
clusters of mussels on black smoker chimneys.
Eastern Pacific vent communities are dominated
by tall, fat tubeworms called Riftia pachyptila.
Northeast Pacific vent communities are dominated by “bushes”
of skinny tubeworms called Ridgea piscesae.
Central Indian vent communities are populated by Western
Pacific-type fauna, but also have North Atlantic-type shrimp species.
Arctic Ocean
The Arctic Ocean has never had deep connections with other major oceans. It
may harbor fundamentally different vent animals that evolved in isolation over
the past 25 million years.
Caribbean
In this region, methane seeping from the seafloor also supports animal communities.
Did animals migrate between “cold seeps” and nearby hot vents over
evolutionary history?
Southern Ocean
The Drake Passage may act as a key link or bottleneck for larval dispersal between
the Atlantic and Pacific. Whale carcasses and shipwrecks (such as Shackleton’s
Endurance) may offer refuges or stepping-stones between vents.
Chile Rise
This region has a variety of chemosynthetic habitats and geological features
in close proximity. How do seafloor populations diverge or converge at this
triple junction on the “highway” of mid-ocean ridges?
South Atlantic
Powerful currents and huge seafloor chasms (fracture zones) may act as barriers
blocking the dispersal of vent larvae and disconnecting vent populations in
the North and South Atlantic.
Western Pacific vent communities are dominated by barnacles
and limpets, as well as hairy gastropods, shown left.
On the Seafloor, Different Species Thrive in Different Regions
Soon after animal communities were discovered around seafloor
hydrothermal vents in 1977, scientists found that vents in
various regions are populated by distinct animal species.
Scientists have been sorting clues to explain how seafloor
populations are related and how they evolved and diverged
over Earth’s history. Scientists today recognize distinct
assemblages of animal species in six major seafloor regions
(colored dots) along the system of volcanic mountains and
deep-sea trenches that form the borders of Earth’s
tectonic plates. But unexplored ocean regions remain critical
missing pieces for assembling the full evolutionary puzzle.
Click
on the dots and puzzle pieces below for more details.
