Well, what I get out of this significant exchange of
opinions is that:
(1) A lujvo is impracticle. While one based on {xamsi jukni}
is tempting, not all crabs inhabit the sea. A lujvo of sufficient
precision would be just too long.
(2) A type III fu'ivla like {juknrbraxiura} is problematical given
the dispute as to whether a crab is really a {jukni}.
(3) That leaves a type IV fui'vla. Choosing one based on
a word that is recognizable in only one 'minor' or a few
'minor' languages just doesn't make sense to me.
It should come from either English or Chinese and
be vaguely recognizable in at least several other major
languages. Failing that, Linnaean is the way to go. The
fact that it is based on Latin is incidental. If it was based
on Pidgeon English, it would still be OK.
So for me 'crab' is {braxiura}.
totus