1. The Oldest Vertebrate on Earth
Greenland sharks hold the extraordinary title of being the oldest vertebrates on the planet. With some individuals estimated to be close to 400 years old, they outlive even the most venerable whales and giant tortoises. Their extended lifespans have stunned researchers and prompted a global quest to understand what sets these sharks apart from all other long-lived animals. For more on their age-defying existence, visit National Geographic.