Deep Sea Life in the Southern Ocean

The Southern Oceans are largely unexplored, especially at depth. The Australian CSIRO Marine and Atomspheric Research Unit conducted a survey in 2006-2007 that added greatly to our knowledge of the life that exists 3000 meters below the surface of the ocean. Their research vessel sampled an area in the SouthEast Commonwealth Marine Reserve Network that lies about 185 km south of Tasmania. The seascape there is studded with extinct volcanoes and deep ocean trenches. A deep diving robot was used to collect samples. So far over 274 new species of fish, crustaceans, molluscs, echinoderms, sea spiders (pycnogonids) and sponges have been identified. Fully 70% of the species found are new to science. Another 86 species were found that were new to that region.

Since then, in 2009, there has been another voyage of discovery to the Tasman Fracture Zone in the same Marine Reserve Network, where more new species have been found. This was a joint venture between the CSIRO and the California Institute of Technology plus the American Woods Hole Oceanographic Institute, which provided JASON, an underwater remotely operated submarine, for the survey.

The extinct volcanoes, also known as seamounts, and the deep sea trenches, provide much better habitats than the flat, muddy abyssal plains that make up the majority of the deep ocean bottom. The seamounts provide a solid substrate for the growth of sedentary animals such as corals and sponges and these in turn provide food and habitat for molluscs, crustaceans and fish. Since these communities live well below the light zone, plants are not found here and the food chain is dependent on the ‘rain’of organic matter from the surface. These are picked up by the filter feeders such as worms and sponges. On these live molluscs and crabs, while starfish and fish prey on them in turn.

Vast beds of extinct corals have also been found, indicating that this area of the ocean was once much warmer and shallower. These extinct corals are about 10,000 years old and studies of these will reveal much about former climates and plate tectonic movements. Some live coral beds have been found at depths of around 1200 meters, including a bright red specimen called a gorgon’s head coral, from its resemblance to the mythical gorgon. Unfortunately many of these beds appear to be dieing and scientists speculate that the acidification of the oceans due to climate change may be responsible.

Even though it is dark and cold at these depths, many of the animals are brightly colored, including bright orange starfish and purple spotted anenomes. Some of the animals are larger than their shallower counterparts. A carnivorous sea squirt was found that was half a meter tall and many of the sponges and gooseneck barnacles are also larger than normal. One waffle cone sponge was more than two meters tall.

Photos of some of the wierd and wonderful new species that have been found in this rich and unique seascape can be seen at This is only the beginning as many more new species will undoubtedly be discovered in this vast unexplored ecosystem. Discovery and identification is only part of the picture though. We must also work to slow climate change and teh negative effects it will have on all ocean and terrestrial ecosystems.