They're tutorials for object-oriented programming. With animals. Highly beginner-friendly. The kind you'll find in pretty much every for-dummies programming book. Why would you need/want to read such a tutorial more than once?
in reply to perldoc deleted modules
Once you know the concepts of OOP, the meat is in perlobj. It has everything you need to know, in a format that doesn't make you cringe.
(It's questionable whether animals are any good for teaching the concepts of OO, or whether they actually impede learning...)
(Okay, perltooc seems to contain some interesting content, and its deletion might have been a bad idea)