[Lee Stewart]

You've seen pictures and videos of whales (and manta rays) breaching. It takes a huge amount of energy to lift that kind of weight out of the water. So why do they do it? They do it for a number of reasons:

When in pods, it's a form of communication; "come here, I found food." If it's done near a school of fish, they can stun/kill a whole lot of them at once. When loners do it, it's a way of removing parasites from their skin.