East Usambara tree-hole crab (IMAGE) University of Cambridge Caption Hundreds of Eastern Arc species exist nowhere else on Earth, including the East Usambara tree-hole crab, whose use of tree holes for moulting produces water that is used locally for treating calcium deficiency during pregnancy. Credit Julian Bayliss Usage Restrictions With credit 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.