Because of their natural color markings that look like smile lines, killer whales always seem happy. Sharks are ugly and look mad. So even though both animals have dagger-like teeth that could easily rip my flesh from my bones, I find myself less afraid of the one who would look happy doing it.
Sea World has also influenced my feelings. At the Shark Encounter, ominous music plays in darkened caverns while sharks eerily encircle the exhibit's guests who find themselves trapped in tunnels well below the surface. At Shamu Stadium, cheerleaders in wet suits dance around to Brittany Spears classics while killer whales leap from the water, playfully launching other cheerleaders into the air. It's hard to misread the message Sea World is sending.
And the last reason that sharks are scarier than killer whales... it's impossible to trust a fish.