<i>Hydra vulgaris</i> (IMAGE) Kyushu University Caption Hydra vulgaris is a tiny cnidarian with a simple anatomy. Collaborative research led by Kyushu University found that, despite lacking a central nervous system, hydras exhibit characteristics at a molecular and genetic level associated with sleep in more evolved animals, indicating that sleep-related mechanisms may have been acquired before the evolution of the brain. Credit Taichi Q. Itoh, Kyushu University Usage Restrictions Only for media and non-commercial use. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.