Inner Planetary Travels. A young Green Turtle, about 60cm, foraging along the reef. It may take a Green Turtle from 20 to 50 years to reach sexual maturity. Aside from  general predation from other marine life, and humans, they are vulnerable to man-made plastic pollution loose upon the seas, much of which resembles the food that they eat. Things work better out here when we are mindful of our habits, and how we dispose of our waste.