danube crayfish female big claw in threaten pose, hornwort vegetation coldwater biotope aquarium, wildcaught

astacus leptodactylus narrowclawed crayfish turkish astacidae rostrum telson pereiopod antenna exoskeleton crustacean appendage decapod harmful nocturnal cultivation aquaculture gravel substrate underwater clearwater weed closeup driftwood sandbed predator omnivore necrophage nature ecology threat unusual fauna widespread aquadesign water wildlife temperate edible instinct behaviour captive controlled conditions ecosystem organic pollution habitat vegetation hardscape destructive space environment biodiversity danube female big claw threaten pose hornwort coldwater biotope aquarium wildcaught domesticated highly adaptable species invasive freshwater inhabitant disorder design