The oligochaetes are thought to have developed from polychaete stock; the leeches, which have the clitellum in common with the oligochaetes, probably evolved from the latter.
Go tswa mo dikwalong tse di leng teng, e tla tlhagelela gore isigubu, kgotsa moropa wa logong, o ka gareng tlwaelegileng mo gareng ga MaZulu gompieno e ne ya kopisiwa, gongwe go tswa mo baagisaning ba bona ba MaThonga.