Scientists studying Antarctic waters have filmed and captured giant sea creatures, like sea spiders the size of dinner plates and jelly fish with six-metre tentacles.

A fleet of three Antarctic marine research ships returned to Australia this week ending a summer expedition to the Southern Ocean where they carried out a census of life in the icy ocean and on its floor, more than 1,000 metres below the surface.

"Gigantism is very common in Antarctic waters - we have collected huge worms, giant crustaceans and sea spiders the size of dinner plates," Australian scientist Martin Riddle, voyage leader on the research ship Aurora Australis, said.

"Many live in the dark and have pretty large eyes. They are strange looking fish," Mr Riddle told local radio.

"Some of the video footage we have collected is really stunning - it's amazing to be able to navigate undersea mountains and valleys and actually see what the animals look like in their undisturbed state," Mr Riddle said.

"In some places every inch of the sea floor is covered in life. In other places we can see deep scars and gouges where icebergs scour the sea floor as they pass by," he said.

The Australian Antarctic Division expedition will help scientists monitor how the impact of environmental change in Antarctic waters, such as ocean acidification caused by rising atmospheric carbon dioxide levels, will make it harder for marine organisms to grow and sustain calcium carbonate skeletons.

"It is predicted that the first effects of this will be seen in the cold, deep waters of Antarctica," said Mr Riddle.

"What we saw down there were vast coraline gardens based on calcareous organisms and these are the ones that could really be lost in an increasing acidic ocean," he said.

Some creatures, which were retrieved from between 200 and 1,400 metres below the surface, weighed up to 30 kilogrammes, while some 25 per cent of the sea life chronicled was previous unknown.

The census of life in the Southern Ocean is known as the Collaborative East Antarctic Marine Census (CEAMARC). The French and Japanese ships examined the mid and upper ocean, while the Australian ship studied the ocean floor.