Blindsight (Ex): Porpoises can "see" by emitting
high-frequency sounds, inaudible to most other creatures, that
allow them to locate objects and creatures within 120 feet. A
silence spell negates this and forces the porpoise to rely on its
vision, which is approximately as good as a human's.
Skills: Porpoises gain a +4 racial bonus to Spot and Listen
checks. *These bonuses are lost if blindsight is negated.