It is weird, but it's great fun to dig for when you're a kid (and pronounced gooey duck, if you didn't know). They're incredibly fast, so very hard to catch. There's even an old song about them: You can hear the diggers say as they're headed for the bay/"O, I gotta dig a duck, gotta dig a duck a day"
. I've never caught one myself, but my sister did when we were kids!