SYDNEY, May 2 (Reuters) Two polar bear cubs born a week ago at Sea World in Australia’s Gold Coast are expected to make their public debut in three months time, but staff have seen the blind and toothless pair suckling milk from their mother inside their den. Sixteen-year-old mother Liya delivered her second litter on April 26, and the cubs, which have still to be named, weigh about 600 grams and are 15 centimetres long. Fully grown they could stand as tall as standing as tall as 11 feet (3.35 meters) and weigh up to 1,400 pounds (635 kg). “Liya and the cubs will spend the majority of these early months in the maternity den at Sea World,” said Sea World Director of Marine Sciences Trevor Long. The cubs are expected to leave the den in July. Polar bears currently number about 26,000, but their population is expected to fall by a third over the next 35 to 40 years due to melting sea ice in the Arctic, scientists said at a meeting of the American Geophysical Union last December. REUTERS