Three species of crayfish are present in Finland, Astacus astacus (Noble grayfish), Astacus leptodactylus (Danube crayfish) and Pacifastacus leniusculus (Signal crayfish), for your question about 'Why?', I can't answer anything else than the climate and water conditions are suitable for these species of crayfish.
Crayfish
Crayfish are known as both crayfish and yabbies in Australia. "Yabbies" are freshwater crayfish, often found in rivers, creeks and dams in rural areas.
My older crayfish died and my littler crayfish has not yet how do/can they die?
Do crayfish have tarritoris
protects the crayfish
Crayfish are omnivores.
Crayfish are related to small lobsters. Here is a link for pictures of crayfish. http://mackers.com/crayfish/pics.htm
Crayfish are invertebrates.
the crayfish resembles a lobster
No, a crayfish is not a mollusk. It is an arthropod.
what is the texture of crayfish
Crayfish-ess.