crabs (IMAGE) The University of Hong Kong Caption Large crabs, such as Chiromantes haematocheir, constantly rework the sediment, providing nutrients and oxygen to the mangrove trees. Credit Stefano Cannicci Usage Restrictions N/A License Original 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.