An Alligator Snapping Turtle can bite off yr hand ok 
and it has a
nasty temper
Rays if you handle them properly are very gentle one and allow
you to pet them
Sorry... pets are pets. I'm not about to put my life on
the line or lose any limbs, over some pet! 
There are so
many pets out there that are cute and who don't pose a threat to
life or limb. Dogs, Cats, Rabbits, Chinchillas, Hermit
Crabs... A bit silly and a totally unnecessary waste of life
to die from, say, a temperamental pet Tarantula who decided to bite
the owner. 
