Leatherbacks sea turtles are incredible beasts. Little-changed in the last 70 million years, these ocean-going turtles can grow up to 1,000 pounds on a diet of just jellyfish. But their size doesn't protect them from human dangers Leatherbacks can get tangled in fishing gear and drown, or die after eating plastic trash. Their nests are threatened by poachers and climate change. It's up to us to protect these jelly-loving giants.