http://pics.livejournal.com/minosan/gallery/00002stz Most people think of crabs as those cute deflated football-shaped things drawn on menus, and about the size of your fist. Not Minosan crabs.
The blue ones like to climb trees and pounce on their prey. Normally, humans are much too large to be seen as prey, but there are the occasional reports of a starved crab trying its luck. Deaths are exceedingly rare from this, although maulings and disfigurement are not unheard of.
The black ones, likely from Road taint, are inedible, viscious, and tend to grow larger. Some of been sighted the size of a pony. Deaths from these recent invaders are more common.