Some creatures have blindsight, the extraordinary ability to use a nonvisual sense (or a combination of such senses) to operate effectively without vision. Such sense may include sensitivity to vibrations, acute scent, keen hearing, or echolocation. This ability makes invisibility and concealment (even magical darkness) irrelevant to the creature (though it still can't see ethereal creatures and the creature must have line of effect to a creature or object to discern that creature or object). The creature usually does not need to make Spot or Listen checks to notice creatures within range of its blindsight ability. This ability operates out to a range specified in the creature description.
- Blindsight never allows a creature to distinguish color or visual contrast. A creature cannot read with blindsight.
- Blindsight does not subject a creature to gaze attacks (even though darkvision does).
- Blinding attacks do not penalize creatures using blindsight.
- Deafening attacks thwart blindsight if it relies on hearing (as a bat's echolocation ability does).
- Blindsight works underwater but not in a vacuum.
- Blindsight negates displacement and blur effects.
Unless noted otherwise, blindsight is continuous, and the creature need do nothing to use it. Some forms of blindsight, however, must be triggered as a free action. If so, this is noted in the creature's description. If a creature must trigger its blindsight ability, the creature gains the benefits of blindsight only during its turn.