3e SRD:Swallow Whole
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The creature can swallow opponents it holds (see Improved Grab, above). If it makes a second successful grapple check after a grab, it swallows its prey. Unless otherwise noted, the opponent can be up to one size category smaller than the swallowing creature. Damage is usually bludgeoning, often accompanied by acid damage from the creature’s digestive juices. The consequences of being swallowed vary with the creature and are explained in its descriptive text.