Well - you've opened a tin of worms!! pun intended
In Australia there are not only numerous types of crayfish, but also numerous names for them - even for the same type!! More on this later.
To quote from the article in the link below, "Australia has one of the richest collections of freshwater crayfish in the world. All of our species belong to the family Parastacidae, which is found in Australia, New Guinea, New Zealand, Madagascar and South America.
Our freshwater crayfish range from the largest to some of the smallest in existence. The giant Tasmanian crayfish (Astacopis gouldii) grown to 6.3 kg [I make that to be almost 14lb!] and the Murray River crayfish (Euastacus armatus) grows to 2.7 kg [call it 6lb].
Back to names - here's those of which I am aware:
- Crayfish, Cray - Western Australia (WA) - large, spiny saltwater species without claws
- Lobster - New South Wales (NSW) - large spiny saltwater species without claws
- Yabby, Freshwater Crayfish - NSW, WA & elsewhere - small freshwater species with claws
- "Jilgie", "Coonack" (spelling?) - WA - small freshwater species with claws, often confused with yabbies - and, in many cases, often the same thing! Usually olive green.
- Marron - WA - mid to large size freshwater species with claws. Distinctive black colour.
- Redclaw - Queensland (QLD) - mid to large size freshwater species with distinctive red claws.
Further info in the following link (a government aquaculture site): http://www.fisheries.nsw.gov.au/aqu/fw/fw_crays.htm
and here: http://www.amonline.net.au/factsheets/crayfish.htm
(a museum site that highlights my incorrect spelling above. Sorry!)