Considered the world's largest land-based arthropod (an invertebrate critter with an
exoskeleton), the coconut crab is something of a daunting creature. 
Picture a roach with body armor.  This video, uploaded by earthtouch
on December 16, 2009, shows that the coconut crab starts off rather small... and grows some pretty dangerous claws...

I've never seen one of these in person, though I have had large land crabs in my back yard...

If you've ever encountered a giant crab let us know!

More fun (and educational) animal videos can be found here!