Kalmar "Ornithorhynchidae" tana nufin dangin dabbobi masu shayarwa da aka sani da monotremes, wanda ya hada da platypus ( Ornithorhynchus anatinus) da nau'in echidnas (Tachyglossus da Zaglossus). Wadannan dabbobin sun sha bamban wajen yin ƙwai a maimakon su haifi ƙuruciya, haka nan kuma suna da wasu siffofi daban-daban, kamar lissafin agwagwa da ƙafafu masu ɗigo. Sunan "Ornithorhynchidae" ya samo asali ne daga kalmomin Helenanci "ornithos" ma'ana "tsuntsaye" da "rhynchos" ma'ana "snout," wanda tare yana nufin bayyanar kamar tsuntsu na lissafin platypus.