Authorities in southern China have released 276 illegally acquired horseshoe crabs back into the sea, local media reports. Horseshoe crabs are categorised as a Class II protected species in China, making it illegal to kill, transport or trade them. The crabs were seized on December 15 from a shop in Beihai, a port city in the Guangxi Zhuang autonomous region, during a routine inspection, China News Service reported on Tuesday. Police officers from Guangxi’s frontier defence force worked with the local fisheries department to release the crustaceans off the coast of Beihai a few days later. Hong Kong WWF fun run for endangered species Horseshoe crabs, also known as “living fossils”, can be traced back about 445 million years. They have great medical value because their bright blue blood contains amboecytes, which are used to test for the presence of endotoxin, a poison found in most bacteria. But over-harvesting and the destruction of habitat has led to a reduction in their numbers. There are four existing species of horseshoe crabs in the world: one is found along the Atlantic Coast (North America and Mexico), and the others in the waters off Japan, China and southern Sabah on the Malaysian island of Borneo.