Bowhead whales are the longest living mammals, a rockfish and Japanese koi are the longest living fish, and the Greenland shark is the longest living vertebrate. Invertebrates like quahogs can also live hundreds of years, and one set the record at 507 years. Detailed graphics, diagrams and video images help us learn about the immortal jellyfish, the effects of slower metabolism, the importance of the number of neurons in the cerebral cortex, and unlocking secrets to living longer and healthier lives.