Pearl (8) was all over this book. She read it cover to cover in one sitting, and was walking around the house for days afterward spouting the more memorable facts. For example, that camels fight by throwing up on each other. This made for some interesting family fights over the next two days...
Back matter: Glossary, index, and additional list of books to find out more.
All of these facts could be found independently, but collecting the grossness all in one place was a great fusion move on the traditional animal menagerie book. Grossness is subjective, and some of these things aren't really a gross-out (sapsuckers), but they all deal with bodily functions.
What is the role of sources in a book like this? We would expect factual accuracy and good research, but there's not much here to demand any serious knowledge of science. And would there need to be sources on each double page spread? This is the same question I have for the DK Eyewitness series--each page turn may be a new chapter with new sources.