Is the Duchy of Lancaster a Part of the Royal Family?

There are still vestiges of older d monarchial rates that are still around in britain and around the royal family. So specifically now, when it comes to king charles, he now, by virtue of being the monarch, if i understand correctly, owns the duchy of lancaster. And yet, this extends to other sort of strange kinds of aspects of royal ownership have come across. Briton swans, for example, apparently, are owned by the monarch or they are as a classification of royal fish, whales, dolphins, sturgeons,. That's kind of crazy. Am, it's not as crazy as it sounds. Like wise, swans?