There is so much we don't know

Bizarre carnivorous sea squirts, large spider-like creatures and an ancient fossilised coral reef have all been found in a voyage into ultra-deep Australian waters.The scientific examination Chronology of the Tasman Fracture, a four kilometre-deep crack in the earth's crust off the coast of Tasmania's southwest, has led to the discovery of creatures never seen before."A thing that was really surprising was the diversity of life down there," said Dr Ron Thresher from the CSIRO, who took part in the trip."We really didn't know what to expect in these really deep areas. It could have been anything from bare mud to lush communities. It was really a shot in the dark."Never before have life forms at such depths in Australia's oceans been studied.Using a remotely-operated submarine about the size of a small car to collect samples and data, the scientists took photos and film at different depths.At up to 3,000 metres were thousands of sea spiders, creatures about 30 centimetres in diameter that look like land spiders but are in fact unrelated.At 3,500 metres were millions of sea anemones, Dr Thresher revealed."They had never been described before. They had never even been observed before," he said."The entire bottom was covered in these things as far as you can see and it was just completely unexpected to see this huge dominant community down there."Expedition leader Jess Adkins, from the California Institute of Technology, said the deepest life forms observed were anemones living at about 4,050 metres down."Almost immediately we saw there were things living in the sediment," Professor Adkins said.There were also carnivorous sea squirts half a metre high, which trap small fish and other creatures, and differ from most other sea squirts, which filter feed.In depths from about 1,000 metres to shallower water was a reef of black, dead coral that dated to more than 10,000 years old.But for the scientists one of their most bizarre discoveries was what they did not find on the ocean floor.Dr Thresher said the team of Australian and US researchers who took part in the $US2 million ($A3 million) voyage had expected to find coral skeletons that were hundreds of thousands of years old lying in very deep depths."One of the main reasons we went out on this cruise was to find fossil corals so we can reconstruct long-term changes in oceanography and climate, so we spent a lot of time looking for these things all over the place," he said."We looked down around 3,000 metres expecting to find vast quantities of these things and they were all gone."The living ones are there, but the dead ones are simply missing. Either something really weird is going on with the water chemistry or it is a brand new community. That just doesn't seem to make any sense."Something very bizarre is happening at the bottom of the Tasmanian fracture zone, and it is going to take us a long time to work that one out."He said it was possible some layers of deep water were being affected by climate change."It is entirely possible we are getting a water mass signal that is tracking some sort of long-term climate change."That is speculative. The few bits (of coral) we picked up looked sufficiently weird. It looked like something weird was going on chemically. We will try and work that out," Dr Thresher said.The bulk of the funding for the trip, which occurred from December 16 to January 17, came from the US National Science Foundation, with extra money contributed by the CSIRO.