echidna (n.) Look up echidna at Dictionary.com
Australian egg-laying hedgehog-like mammal, 1847, usually explained as from Greek ekhidna "snake, viper," from ekhis "snake," from PIE *angwhi- "snake, eel" (cognates: Norwegian igle, Old High German egala, German Egel "leech," Latin anguis "serpent, snake").

But this sense is difficult to reconcile with this animal (unless it is a reference to the ant-eating tongue), and the name seems more properly to belong to Latin echinus, Greek ekhinos "sea-urchin," originally "hedgehog" (in Greek also "sharp points"), which Watkins explains as "snake-eater," from ekhis "snake."