Literature Circle: Life of Pi 1-22

Before I started to read this book I saw on the back that it was about a young boy that was trapped in a little row boat with a 400 pound tiger. But when I read the first few pages it started to talk about the three toed sloth and about his college Religious and Zoology study courses that he took. I was kinda confused but then as I read on it kinda made since. It seemeed like as Mamaji was teaching him to swim for a good reason. Mamaji was also an Olympic swimmer.

I'm confused about Chapter 4 why he's naming alot of fruit and a lot of animals; mainly on page 20.