<P> Australia has over 100 species in a dozen genera . In Australia, many of the better - known crayfish are of the genus Cherax, and include the marron from Western Australia (now believed to be two species, Cherax tenuimanus and C. cainii), red - claw crayfish (Cherax quadricarinatus), common yabby (Cherax destructor) and western yabby (Cherax preissii). The marron are some of the largest crayfish in the world . They grow up to several pounds in size . C. tenuimanus is critically endangered, while other large Australasian crayfish are threatened or endangered . Australia is home to the world's two largest freshwater crayfish--the Tasmanian giant freshwater crayfish Astacopsis gouldi, which can achieve a mass of over 5 kilograms (11 lb) and is found in rivers of northern Tasmania, and the Murray crayfish Euastacus armatus, which can reach 2 kilograms (4.4 lb) and is found in much of the southern Murray - Darling basin . </P> <P> In New Zealand, two species of Paranephrops are endemic, and are known by the Māori name kōura . </P> <P> Fossil records of crayfish older than 30 million years are rare, but fossilised burrows have been found from strata as old as the late Palaeozoic or early Mesozoic . The oldest records of the Parastacidae are in Australia, and are 115 million years old . </P> <P> Some crayfish suffer from a disease called crayfish plague, caused by the North American water mould Aphanomyces astaci which was transmitted to Europe when North American species of crayfish were introduced there . Species of the genus Astacus are particularly susceptible to infection, allowing the plague - coevolved signal crayfish to invade parts of Europe . </P>

How many different types of crayfish are there