How about the Latin names for crab and swan (whatever those names are)?
cycneus or cygneus -a -um [belonging to the swan].
cygnus -i m. [the swan].
olor -oris m. [swan].
olorinus -a -um [of a swan].
cancer -cri m. [crab; a sign of the Zodiac]; meton. , [the south, or summer heat; the disease cancer].
caris -idis f. [a kind of crab].
nepa -ae f. [a scorpion; a crab].
spinosus -a -um [of thorns , thorny, prickly]; of style, [crabbed, obscure]; of feeling, [anxious].