G'day,
http://www.askabiologist.org.uk/answers p?id=14332
I have been told by the program coordinator of the 'Tamar Island Resource Managemant' Launceston, Tasmania that those squiggles in the sand are most likely made by polychaetes.
However there are 10.000 species of polychaetes but there are also a few polychaete worm experts around Australia. Maybe we can get clue from the experts which species occur on the north coast of Tasmania around Weymouth.
Since I have now a fair idea what to look for I'll try to catch some of those critters.
Regards,
Christina