eye_of_the_tiger, the Great White sharks don't eat the guests because it's a myth that they are maneaters. Sometimes in the wild, they make attack a surfer because they mistaken them for prey, but they usually spit them back out again. I guess Microsoft wanted to make it more realistic so that's why the sharks don't eat anyone.
In ZT2, you shouldn't feed a live lizard to any user-made animals that came out before AA. They just hunt them for hours at a time, and get really hungry, thirsty and miserable.