Walanyoka ni nyoka wenye sumu wa jenasi Polemon katika familia Lamprophiidae. Wamepewa jina hili kwa sababu hula nyoka wengine wadogo kuliko wao wenyewe. Nyoka hawa sio warefu sana, sm 85 kwa kipeo. Kichwa hakina shingo na mkia ni mfupi sana wenye ncha kama msumari. Rangi yao ni nyeusi au kahawia iliyoiva sana. Kichwa au kisogo kinaweza kuwa cheupe, njano au hudhurungi. Walanyoka huishi katika vishimo au chini ya takataka za majani ambapo huwinda nyoka wengine. Chonge ni meno ya nyuma na zina mitaraza. Wakishikwa na mtu hawawezi kuingiza sumu yao. Kwa hivyo nyoka hawa sio hatari. Polemon acanthias, Mlanyoka wa Reinhardt (Reinhardt's snake-eater) Polemon barthii, Mlanyoka wa Gini (Guinea snake-eater) Polemon bocourti, Mlanyoka wa Bocourt (Bocourt's snake-eater) Polemon christyi, Mlanyoka Mashariki (Eastern snake-eater) Polemon collaris, Mlanyoka kichwa-hudhurungi (Fawn-headed snake-eater) Polemon fulvicollis, Mlanyoka kisogo-njano (Yellow-necked snake-eater) Polemon gabonensis, Mlanyoka wa Gaboni (Gabon snake-eater) Polemon gracilis, Mlanyoka Mwembamba (Graceful snake-eater) Polemon griseiceps, Mlanyoka wa Kameruni (Cameroon snake-eater) Polemon leopoldi, Mlanyoka wa Rwanda (Rwandan snake-eater) Polemon neuwiedi, Mlanyoka wa Kodivaa (Ivory Coast snake-eater) Polemon notatus, Mlanyoka Madoadoa (Spotted snake-eater) Polemon robustus, Mlanyoka wa Kongo (Congo snake-eater) Spawls, S., Howell, K., Drewes, R. & Ashe, J. (2002) A field guide to the Reptiles of East Africa.