small badger, porcupine
貆 centers on a small, spiny mammal: a small badger or porcupine. The two meanings share the idea of a compact, bristly animal.
貆 combines the beast radical 豸 with 亘, which likely provides the sound. The character is used for small, spiny mammals, but the exact historical development is uncertain.
The left side 豸 suggests a clawed animal, and the right side 亘 looks like a spiky back. Picture a small badger or porcupine with bristling spines.
For カン, imagine a can of porcupine quills: can -> カン, and the spiky animal fits the meaning.