This is misleading, Gorillas are technically omnivores. I think elefants are pretty strict vegans, though. When it comes to tortoise I am not quite sure.
A friend of mine had a small garden pool with 2 or 3 tortoises and decided to buy some more fish to add the pool. The day after, half of the fish was gone leaving my friend puzzled. The second day the fish was gone and he understood why: tortoises, at least water ones, are omnivores.