Like anyone with rowdy neighbors, oysters may be feeling stressed thanks to the growing problem of underwater noise pollution and are trying to filter out the racket. New research in PLoS One reveals that oysters will close their shells when exposed to noises along a range of frequencies that includes the sounds emitted by known noise polluters like cargo ships and underwater oil exploration. In oysters, closed shells are an indicator of distress. Under optimal conditions, bivalve mollusks will keep their shells open. Clamping their shells to screen out noise pollution or other artificial irritants could prevent oysters from perceiving important biological cues, said the authors of the study. Oysters "must be able to hear breaking waves and water currents," which could trigger their biological rhythms, said Jean-Charles Massabuau, an author of the study.

374-million-year-old tree fossils discovered in China

Scientists have discovered 374-million-year-old tree fossils from the dawn of Earth's forests — and found that these strange plants literally had to rip themselves apart as they grew. The fossils, described in the Proceedings of the National Academy of Sciences, shed light on the nature of ancient forests and the evolution of the Earth's climate. The Xinicaulis lignescens fossils, discovered in Xinjiang, China, are part of a group of species known as Cladoxylopsida — plants that have no known descendants but are thought to be related to the ancestors of today's ferns and horsetails. They could grow about 30 to 40 feet tall and 3 feet wide at the base; their branches popped out of the top of the trunk, giving it a shape similar to today's palms. These branches sprouted further, tinier appendages that were not yet true leaves.

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