Leatherback sea turtle (Dermochelys coriacea) has a pink spot/white spot on top of its head that act as a "third eye" to help it sense the change in seasons.Every summer, the sea turtle swim thousands of miles from their breeding ground in tropical waters to feed in cooler parts of the ocean - but how does it know how to begin its journey back? Now, a new <a href="https://www.sciencedirect.com/science/article/abs/pii/S0022098114001968" class="on">anatomical study</a> showed that the pink/white spot on top of its head has a markedly thinner layer of bone and cartilage thus allowing the underlying pineal gland of the turtle's brain to sense subtle changes in sunlight that accompanies the changing of the seasons - thus acting as a "skylight" sensor.Image: J. Davenport et al.#turtle #leatherbackseaturtle #thirdeye #eye #pinealgland #anatomy #animalmigration