What, you've never seen animals of not merely different species, but entirely different genus and family create offspring before? It's just your common, run-of-the-mill foxcoon!
Btw, is Fennecoon really a proper translation for アラネちゃん (Arane-chan)?
Well, it's a combination of "アライグマ"/"araiguma" and "フェネック"/"fenekku" into "アラネ"/"arane" with a "-chan" on the end, so if you want to be highly literal, it's basically "Raccnne-chan", but that doesn't roll off the tongue quite as well.
You could probably add the "-chan" in to make it "Fennecoon-chan", though.
