Raƙumi zai iya rayuwa har na tsawon kwana takwas ba tare da ci ko sha ba. Don haka idan raƙumi ya samu inda zai sha ruwa, kasancewar yana da matuƙar buƙatarsa, sai ya sha ya kuma ajiye wani ruwan a cikinsa. Raƙumi yakan iya shan ruwan da ya kai ɗaya bisa uku na girmansa a cikin minti goma kacal, wato kwatankwacin galan 30 kenan.