n medium animal aquatic 

Perception +8; darkvision

Skills Acrobatics +7, Athletics +8, Stealth +7

Str +4 Dex +3 Con +1 Int -4 Wis +2 Cha -3

AC  19; Fort +7, Ref +9, Will +8

HP 24; Resistances physical 3 (except bludgeoning)

Vulnerable to Prone If a creature critically succeeds on a check to Trip the giant crab, the crab is flipped over onto its back in addition to the usual effects. A giant crab that is flipped onto its back has a particularly hard time defending itself; instead of taking the normal –2 circumstance penalty to AC for being flat-footed, it takes a –4 circumstance penalty to AC.

Scuttle [R] Trigger A creature that the giant crab can see targets the crab with an attack; Effect The giant crab scuttles to the side and gains a +2 circumstance bonus to AC against the triggering attack. After the attack resolves, the crab can Stride up to its speed in a straight line as part of the reaction.

Speed 25 feet, swim 15 feet

Melee [>] claw +10, Damage 1d10+4 slashing plus Grab

Constrict [>] 1d6+4 bludgeoning, DC 18

Bestiary 2, page 55.