I've recorded a short, informal video demonstrating how I use MarineLife Keywords. Although the keyword list isn't meant to replace reference and ID books, it does help a great deal in metadata workflow if you already know an animal's common name. In fact, the keyword list works best in conjunction with existing ID books. Once you find an animal's common or scientific name, it's easy to search the keyword hierarchy.
This video is most helpful for Aperture users, but Lightroom users may find it interesting as well since keywording workflow is similar in both products.