great diving beetle, dytiscus marginalis, male hide in dense hornwort vegetation, wide-spread wild freshwater insect

animal aqua aquarium background beetle behavior biotope bug clear closeup coldwater dangerous decorative dense diving driftwood dytiscus eco ecological endemic europe european fauna fish fishkeeping fresh freshwater great grey hide hornwort hunt hunter insect lake live look macro male marginalis moderate natural nature predator protection tank temperate underwater vegetation water weed widespread wild