The first three seahorses born at Shanghai Ocean Aquarium will soon be giving visitors a lesson in nature's eclectic approach to gender roles.

　　"Only the males give birth," said Huang Yanping, an aquatic expert at the Pudong facility.

　　Males become pregnant when a female deposits her eggs in his pouch.

　　The babies, now about 2 centimeters long, and another pregnant seahorse father, which is expected to give birth in a week, are receiving special care in a controlled environment that simulates natural sea conditions. They'll be allowed to join their 20 or so cousins in the aquarium's display tanks as soon as they're old enough.

　　"These creatures are very fragile," Huang said. "In nature, only about 1 percent survive to maturity."

　　Because of their high value in herbal medicines, seahorses are facing a growing threat from excessive capture, said Wang Hong, an official at the aquarium. "We are trying to raise public awareness about the need to protect the creature."