Ahkiok, a Kodiak bear at the Indianapolis Zoo, was found dead in his den early Tuesday morning, zoo officials said.The 21-year-old bear was born at the Pittsburgh Zoo in 1987 and had been at the Indianapolis Zoo since 1988.Kodiak bears can typically live up to 25 years. Adult males are up to 10 feet tall and weigh up to 1,800 pounds.Zoo veterinarians said the animal likely had a blood-clotting disorder that caused his death."This is very sad for the zoo, as well as a loss for our members, visitors and friends," said Michael Crowther, president and CEO of the Indianapolis Zoo. "Over the years, many people had the opportunity to see the Kodiak bears and appreciate their size, strength and unique position and importance to the natural world. Some members of our keeper staff have spent their whole careers caring for these bears."Ahkiok's littermate, a Kodiak bear named Chugach, was euthanized in November 2007 because of a severe degenerative joint disease, zoo officials said.