whistling for dolphins

The Greeks believe that if you whistle, the dolphins will visit your boat. I've tried that and all I get is a dry mouth. The dolphins appear out of nowhere and play around the bow of the boat, especially zipping back and forth right under the bowsprit. I thought that dolphins only show up during the day, but on a night sail south of Thasos Island, a group of three joined us for about 10 minutes. I discovered that dolphins never sleep and scientists are divided about the reason. Some believe that dolphins have a split brain and that one half sleeps at a time. Others think that dolphins take a deep mini-sleep for a couple of seconds and can rest completely at that time. These Aegean dolphins have a long nose and the largest I've seen has been about 3 meters long. Usually there are families with young adults, I call them teenagers. It is always uplifting when dolphins appear. They are so strong, and "happy." Once, my brother, Len, was taking photos of some under the bowsprit and he shouted, "Watch out, CHARLIE is going too fast for them." I laughed. No matter how fast we went, the dolphins were, of course, faster. I shout out to them, "We're mammals also."