FLATWORMS REGENERATING HUMAN TISSUE?

A book about the impact of the sex life of the marine polyclad flatworm and its medical implications for regeneration of human tissue could take out this year's Eureka Science Book Award.

These little known marine creatures occur in all the world's oceans and are particularly common around coral reefs. 'Marine Flatworms: The World of Polyclads' is the first book to be devoted to polyclad flatworms and contains colour photographs of hundreds of specimens. The principal author is Dr Leslie Newman, Research Associate in the School of Environmental Science and Management at Southern Cross University in Lismore. The book reveals groundbreaking research on the flatworms' feeding habits, toxins, mimicry and bizarre sex lives.

"Polyclads are among the simplest of the marine invertebrates and flatworms are among the simplest of all creatures with complex reproductive behaviours. We found what we call 'penis fencing.' This is when the hermaphroditic flatworms approach each other with their penises extended and repeatedly fence and stab at each other. We can only assume this indicates it's a competitive advantage to be a father rather than a mother, though they can be both," Leslie said.

The flatworms are often extremely brightly coloured: yellow, crimson, deep blue, purple, pink, dotted, spotted, striped and frilled, but they are highly toxic. They themselves are predators, but because of their toxicity few animals can eat them and survive. Some worms can shrink themselves flat and slide inside bivalves, making them a pest to commercial aquaculture.

"Flatworms have great economic impact. They can cling to the bottoms of boats and be transported all around the world or their larvae can survive in a ship's ballast. One Japanese species infested the Vancouver mussel industry and decimated it for years," Leslie said.



Dr Newman discovered marine flatworms when she was looking for a way to avoid being tossed about in boats at sea and swimming with tiger sharks, which was all part of her PhD thesis on zooplankton at Heron and Lizard Islands. As she told her co-author, retired Worms Curator with the Queensland Museum, Dr Lester Cannon, she wanted to pursue animals which could be caught with a bucket.

The flatworm form and makeup had eluded scientists' reach, because they had found no reliable way to fix them for study. At a touch from a hand, the flatworms often turn to mucous mush. Leslie and her late husband, Dr Andrew Flowers, discovered a way to fix flatworms flat and intact without destroying them, a world-first. Over 100 species have now been formally described.

"Before our research began, there were only 16 species known from the Great Barrier Reef, we are now at over 500 new species and still counting." Leslie said.

Flatworms also have a remarkable ability to repair and regenerate lost tissues. Leslie found that one fragment containing the basic brain can regenerate a whole new animal, and a large wound can be repaired in 24 hours. This ability to transform itself could have repercussions for human development and repair, in addition to flatworm toxin, which may have implications for cancer research.

"Their toxins are the same as fugu poison, as found in puffer fish which is a Japanese delicacy. One flatworm species in Florida feeds on the mangrove sea-squirt. Scientists have since found a drug from that sea-squirt which has been useful in fighting ovarian cancer. They need tonnes of the sea-squirts to make the drug, but the flatworm has this toxin in far greater concentration. Our quest now is to try to get the flatworms cultivated in captivity, but there is little support for the research," Leslie said.

Dr Newman is virtually the only scientist in the world working with live marine flatworms. The book is now available through CSIRO publishing and retails for $39.95. Leslie and Lester are currently working on a CD-ROM to accompany it.

Further Information: Kath Duncan 02 66203144