The BBC report some interesting observations about progression in play of the dolphin family, of which killer whales belong,
Most mammals seem to enjoy play - but dolphins seem to like making their games as challenging as possible. A killer whale calf learned the trick of luring gulls to the surface of the water with fish. When the gulls landed on the water, the killer whale would then attempt to capture them in her mouth, without killing them.
Once she mastered this skill, she made the task more challenging for herself: instead of waiting for the gulls to land on the water, she tried to capture the gulls on their descent when they were more than a metre above the water surface.
She failed many times but kept going until she got good at it. More often than not, it was the naive juvenile gulls that were caught and subsequently tossed around. The next difficulty level entailed trying to catch the more clued-up, older gulls. As with human children, the activity itself, not just the outcome, has to be fun.
