Turtles in our Midst

When they were first brought in from a Chinatown petshop two years ago these turtles have shell more green than today but remain keeled with a red mark somewhere behind the eyes, and maybe classified under the sub-specy of Pseudemys scripta elegans. These young reptiles, less than two inches upon hatching have a delicate sense of touch, poor hearing, good close-up vision, good sense of smell and low intelligence. Although they thrive on chopped earthworms, raw hamburger and guppies, the current diet consists of pellets from the store. They never get to learn eating shredded lettuce, just plain pellets procured from a local Petsmart store.
On weekends, I would guard them walking by the backyard. At one time, we left them for a few minutes and the duo were able to cross the neighbor’s fence, slipping their small shell in the process. So, now, more often than not, we left them to themselves but inside a spare auto tire complete with water they can waddle into.
These reptiles make a hissing sound that without looking at the animals you might pressume some snake are just nearby. But they do the hissing thing if only threatened like holding or poking at them. Other than that, they are just so peaceful if let alone. They are too shy they hid their head once poked. At over four inches in length, they have more than doubled since hatching. They could live for about fifty years, long enough to get acquainted-- pet and owner- getting attached that much length of time!
Now, watching at Andrew Zimmern of Travel Channel flip over the shell, sip the soup and chew the head of a turtle, can I ever do the same for these two?