Danube crayfish

 The Danube crayfish Astacus leptodactylus – in Poland called also the marsh crayfish, long-clawed crayfish or tailor. 

This species originally occurred on the drainage basin of the Black Sea and Caspian Sea, so it was native species to the south-eastern part of pre-war Poland.
Identification of this species is possible based on the following features: the carapace covered by nodes, completely closing claws (resembling scissors) with creamy white bottom.
The biology of this species is similar to the biology of the noble crayfish. The marsh crayfish shows lesser habitat requirements, and it tolerates more eutrophic waters with more sludgy bottom. 
The Danube crayfish is endeared species similar to the noble crayfish.