marine flatworm - planaria, crawling on the glass, black sea

animal animalia annelida biological biology bristles chaetopteridae climbing crawling education eye flatworm flatworms life marine worms microscope microscopic nimertina ocelli oligochaeta pharynx planaria planarian planeria polychaeta polychaetes pond rainforest ringed science segmented spot system tiny turbellaria turbellarian water zoological zoology