Pacific sleeper sharks, a large, slow-moving species thought of as primarily a scavenger or predator of fish, may be preying on something a bit larger -- protected Steller sea lions in the Gulf of Alaska. A new study has found the first indirect evidence that this cold-blooded shark that can grow to a length of more than 20 feet -- longer than a great white shark -- and may be an opportunistic predator of juvenile Steller sea lions....