Ключевые слова: alternative, ancient, animal, annelid, annelida, anxiety, background, biology, black, blood, bloodsucking, care, clitellum, closed, comprise, crabs, dangerous, disgust, doctor, earthworms, education, glass, healing, health, hemolymph, heparin, hermaphrodite, hirudinea, hirudotherapy, invertebrate, jar, leech, leeching, medical, medicalleech, medicinal, medicine, nature, paraphyletic, parasite, parasitic, science, segmented, skin, sucker, suction, therapy, water, wet, worm,