Where does “蟹” come from?

蟹 (Japanese) comes from Japanese 殻 — shell, crust, chaff; husk, hull; cinders, ashes.

蟹 (Japanese): a crab

Definitions

Step	Language	Word	Meaning
1	Japanese	殻	shell, crust, chaff; husk, hull; cinders, ashes

蟹 — Etymology, Origin & Word History | Etymology Explorer