weasel, skunk, ermine
鼬 centers on small, slender carnivorous mammals known for their musky odor: weasels, skunks, and ermines. The meanings are closely related animals within the same broad family.
鼬 combines 鼠 (rat/mouse) with 由, which likely contributes the sound. The character denotes a weasel-like animal, a member of the rodent-like mustelid family.
The left side 鼠 suggests a rodent-like creature, and the right side 由 (reason) hints at the reason for its smell: a weasel or skunk. Picture a mouse-like animal with a distinctive musky reason for its reputation.
For ユウ, imagine a weasel letting out a long 'yuuu' sound as it scurries away: yuuu -> ユウ.
weasel (esp. the Japanese weasel, Mustela itatsi)
Japanese weasel (Mustela itatsi)
Korean yellow weasel (Mustela sibirica coreana)
polecat (Mustela putorius); ferret; fitch
mongoose
cut in the skin caused by a vacuum formed by a whirlwind
snubnose brotula; armoured cusk (Hoplobrotula armata)
ferret badger (esp. the Chinese ferret-badger, Melogale moschata)
false indigo (Amorpha fruticosa); bastard indigo; leadwort
goatsbeard brotula (species of ophidiiform fish, Brotula multibarbata)
tiger shark (Galeocerdo cuvier)