narrow-clawed crayfish show huge claw on sand gravel substrate, hornwort vegetation planted european biotope aquarium, wild caught

astacus leptodactylus danube crayfish turkish astacidae rostrum telson periopod antenna exoskeleton crustacean appendage decapod molting harmful nocturnal cultivation domesticated aquaculture underwater clearwater weed ceratophyllum demersum 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 internal filter hardscape destructive space environment biodiversity narrow-clawed show huge claw sand gravel substrate hornwort vegetation planted european biotope aquarium wild freshwater species highly adaptable invasive animal dark background