TONGUE-eating fish parasites, big-clawed shrimps and rare jellyfish that float upside down - these underwater treasures were discovered off the coasts of Australia as part of an international census of marine life.

The Australian Institute of Marine Science has released the initial results of its survey of Australian reefs, including the Great Barrier Reef off Queensland and Ningaloo Reef in northwestern Western Australia.

The study is part of the Census of Marine Life, a global network of researchers engaged in a 10-year initiative to explain the diversity, distribution and abundance of marine life in the oceans, past and present.

Murdoch University senior research fellow John Huisman, an expert on marine algae of tropical WA, and PhD student, Rainbo Dixon, were involved in the study, having collected, identified and taken DNA samples of species, many new to science.

"You need to know what's out there if you want to know whether the environment is changing," Dr Huisman says.

"There is a huge diversity out there. For example, plants on land essentially consist of one group whereas in the sea marine algae consist of up to 12 groups."

Dr Huisman says there is a big push to ‘barcode’ marine species, not just for taxonomic importance but therapeutical benefits.

Bioprospecting marine plants and animals promises novel compounds that can be synthesised in laboratories to make drugs to fight cancer, diabetes and other diseases and disorders.

He says the census would provide a valuable inventory or database against which drug companies could check their compounds.

The expeditions also help mark the International Year of the Reef, and include the systematic scientific inventory of spectacular soft corals called ‘octocorals’, for the eight tentacles that fringe each polyp.

Researchers believe between one-third to half of the hundreds of soft corals found are species new to science. They dominate some areas studied, covering up to 25 percent of the ocean floor and providing important habitats for other species.

“Corals face threats ranging from ocean acidification, pollution, warming to overfishing and starfish outbreaks,” AIMS chief executive officer Ian Poiner said in a statement last week.

“Only by establishing a baseline of biodiversity and following through with later censuses can people know the impact of those threats and find clues to mitigate them.”

Other discoveries include:

- Around 300 soft coral species, up to half of them thought to be new to science
- Parasitic isopods, called tongue-biters or vultures of the sea because some feed on dead fish. The cymothoids invade a fish and eat its tongue, replacing it by attaching itself to the host's mouth
- Rarely-sampled amphipods of the family Maxillipiidae, featuring a bizarre whip-like back leg about three times the size of its body
- New species of tanaid crustaceans, shrimp-like animals, some with claws longer than their bodies
- The rare Cassiopeia jellyfish, tentacles waving in the water column in a posture that enables symbiotic algae in its tentacles to catch sunlight for photosynthesis.

Dr Poiner chairs the scientific steering committee of the Census of Marine Life-affiliated, which is expected to release its first global census in October 2010. Details of the census are available here.