Orca vs Sharks

Some recent footage was caught off the coast of New Zealand of at least one Orca fighting and/or attacking a number of sharks.  It seems the footage may be of one of a pod of whales, these sharks killers, and that its role is to chase members of this shark school away from the beach where they can be more easily killed and eaten by the rest of the pod.  Here's a Yahoo News video account of the action.

For your own setting, sometimes when you want to show the dangers in an area but without directly confronting the characters, having a couple of the local heavyweights duke it out nearby so that it can be witnessed is a fun alternative.  One of my favorite storytellers, Ray Harryhausen, did this regularly in his stop-motion animated film sequences.  This is a good way for a GM to introduce the full range of hazards and creatures, rght up to the top of the food chain, to players even when they have rather fledgling characters.  Have fun!