Deep-Sea Mussels Swap Tidal Rhythms for 24-Hour Cycle in Lab, Study Finds

In the perpetual darkness of deep-sea hydrothermal vents, the mussel Bathymodiolus azoricus, living 1,700 meters (5,600 feet) below the surface, surprisingly follows a 24-hour rhythm when brought into the laboratory. This discovery challenges assumptions that organisms in lightless environments lack circadian clocks. Researchers found that the mussels' cells exhibit daily cycles, suggesting an internal timekeeping mechanism that may be synchronized by tidal or other environmental cues in their natural habitat. The study, published in a peer-reviewed journal, highlights the adaptability of biological clocks in extreme environments. Understanding these rhythms could shed light on how deep-sea organisms cope with fluctuating conditions, such as changes in food supply from vent fluids. The findings may also inform broader research on circadian biology and its evolution across species. As scientists continue to explore the deep ocean, such insights reveal the hidden complexity of life in one of Earth's most challenging habitats.