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Seamounts are mountains rising from the sea floor to below the surface. They are the remains of extinct ocean-floor volcanoes that last erupted many million years ago. Most are found rising from a seafloor of 1,000–4,000 metres depth. There are an about 100,000 seamounts in all the world’s oceans, with only a few having been studied. Seamounts come in a wide variety of structural shapes, from conical to flat-topped to complexly shaped. Some are built very large and very low others are built more steeply.

Australia’s largest cluster of seamounts is found about 50 to 170 km off the coast of southern Tasmania in an area known as the Huon Commonwealth Marine Reserve. It contains about seventy seamounts. This reserve ranges from 70 to 3,000 metres below sea level and occupies an area of about 370 square kilometres. Some of these seamounts are up to 25 kilometres across and rise 500 metres from the sea floor.


Seamount mapping
3D image of the seamounts and the
South Tasman Rise off Tasmania
Image provided byf the National Oceans Office
and Geoscience Australia




Thanks to
I would sincerely like to thank the many members of the Flickr community who have given me permission to use their wonderful images for this unit. Their contributions really make this unit come alive!

Location of Tasmanian seamounts
Davidson Seamount: The Biology of an Underwater Mountain
Over the last two decades, marine biologists have discovered lush forests of
deep-sea corals and sponges growing on seamounts (underwater mountains)
offshore of the California coast. It has generally been assumed that many of
these animals live only on seamounts, and are found nowhere else. However,
new research from MBARI shows that most seamount animals can also be
found in other deep-sea areas. Seamounts, however, do support particularly
large, dense clusters of these animals. These findings may help coastal
managers protect seamounts from damage by human activities.

Next:  Ecology  ...


Ecology and Threats
Some unusual animals
A food web


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