cannibal crabs

Number: 5d10 (2d10)
Alignment: Neutral
Movement: 60'(20')
        Swim: 30' (10')
Armour Class: 8
Hit Dice: 1 hit point
Attack: 1 (claw per 10 individuals)
Damage: 1d6, bleeding, swarm. 
Save: 0th lvl human
Morale: 7
Hoard Class:XX

These brightly-coloured red and purple crabs are a foot across.  When alone, they will flee from larger creatures unless cornered.  In a swarm, they turn vicious, willing to attack anything living of Medium-size or smaller.  Swarms attack with multitudes of ripping pincers that get one attack per 10 individuals to do 1d6 damage.  Each round that the crabs attack, there is a 5% chance that their pincers open a vein, causing 1d3 damage each round to living creatures until injuries are treated or curative magic is used. If a character is swarmed by a whole pack, they must successed in a saving throw vs. death or be  knocked prone and unable to attack under the scuttling mass.  They may stand up next round if successful but must make a new saving throw each round they stand in the swarm.
 
If a swarm is reduced to nine or fewer crabs, they will seek to flee.  The cannibal crabs are known to feed on those creatures they kill.  Though they prefer to feed on land, they will do so in water though their tendency to bleed victims will attract sharks.