SRD:Natural Weapons

Natural Weapons
Natural weapons are weapons that are physically a part of a creature. A creature making a melee attack with a natural weapon is considered armed and does not provoke attacks of opportunity. Likewise, it threatens any space it can reach. Creatures do not receive additional attacks from a high base attack bonus when using natural weapons. The number of attacks a creature can make with its natural weapons depends on the type of the attack—generally, a creature can make one bite attack, one attack per claw or tentacle, one gore attack, one sting attack, or one slam attack (although Large creatures with arms or arm-like limbs can make a slam attack with each arm). Refer to the individual monster descriptions.

Unless otherwise noted, a natural weapon threatens a critical hit on a natural attack roll of 20, and deal double damage on critical hits.

When a creature has more than one natural weapon, one of them (or sometimes a pair or set of them) is the primary weapon. All the creature’s remaining natural weapons are secondary.

A creature’s primary natural weapon is its most effective natural attack, usually by virtue of the creature’s physiology, training, or innate talent with the weapon. An attack with a primary natural weapon uses the creature’s full attack bonus, and its damage includes its full Strength modifier (1-1/2 times its Strength bonus if the attack is with the creature’s sole natural weapon). Attacks with secondary natural weapons are less effective and are made with a –5 penalty on the attack roll, no matter how many there are, and add only 1/2 the creature’s Strength bonus to damage. (Creatures with the Multiattack feat take only a –2 penalty on secondary attacks.) This penalty applies even when the creature makes a single attack with the secondary weapon as part of the attack action or as an attack of opportunity.

Natural weapons have types just as other weapons do. The most common are summarized below.

Bite
The creature attacks with its mouth, dealing piercing, slashing, and bludgeoning damage.

Claw or Talon
The creature rips with a sharp appendage, dealing piercing and slashing damage.

Gore
The creature spears the opponent with an antler, horn, or similar appendage, dealing piercing damage.

Slap or Slam
The creature batters opponents with an appendage, dealing bludgeoning damage.

Sting
The creature stabs with a stinger, dealing piercing damage. Sting attacks usually deal damage from poison in addition to hit point damage.

Tentacle
The creature flails at opponents with a powerful tentacle, dealing bludgeoning (and sometimes slashing) damage.