The Thing About Jellyfish: Parts 2 & 3A

Part Two is just one chapter, "Best Educated Guess," so I started reading Part 3 as well. I read three chapters: "Early Life," "How to Have a Friend," and "Dr. Legs." It's really interesting to pay attention to tense in this book, and how the tense shifts in different parts of the story. Notice how some parts are told in past tense and others are told in present tense. Why the shift? What effect do you think it has on you as a reader?