HOUSTON — The Houston Zoo has announced the death of an 18-year-old African lion that had lived at the zoo for a decade.

The zoo says on its website that the lion, named Jonathan, died early Wednesday morning after veterinarians discovered a “serious blood clotting issue” and a low white-blood-cell count the night before. The zoo says the conditions are not uncommon in older lions.

Jonathan came to the zoo in 2006 after he was rescued from a private owner.

The zoo says he was recognizable to visitors by his “regal mane” and could usually be found resting in the sun surrounded by his pride of three females. The zoo says their African lions serve to educate visitors about the work being done to help save this vulnerable species.