Armed soldiers take aim during an anti-terror drill in Shenzhen, April 9, 2013. [Photo/Xinhua]

An animal expert helps the youngest of a litter of whitetip reef sharks swim in a marine science museum in Yantai city, East China's Shandong province on April 9, 2013. A six-year-old whitetip shark produced quadruplets on the evening of April 8. It is rare for a whitetip to give birth to quadruplets through artificial breeding. [Photo/Xinhua]