“Invertebrate / amphibian”?

The German site Aqua4you has an article about Marmorkrebs that seems to be contain good basic information on caring for Marmorkrebs as pets. I say “seems to,” because I am relying on Google Translate to tell me most of what it says. Maybe that’s why the family is being shown as “invertebrate / amphibian”... though I doubt it. It’s a rather odd grouping. I guess the classification is, “lives in an aquarium but isn’t a fish.”