Green Sea Turtles are ontogenetic. This means that with age, their diet changes. They are predominantly vegetarian except in the first year or so then they are carnivorous. Their omnivorous diet consists of marine grasses, mangrove leaves, and algae. These plants may often contain snails or other small marine organisms that are then also eaten. Because of a diet roughage, these turtles have micoflors living in their large intestine to help breakdown the cellulose that would be otherwise indigestible.
The diet of young hatchlings is very different. While the turtles are young, they are carnivorous. For approximately the first year, the hatchlings prefer chopped bits of fish rather than algae. Because the hatchings are still juvenile turtles, they have not yet developed bacteria in their gut. By eating their parents feces the bacteria will become part of their digestive system as well.